Objectives
At the end of this chapter you should:
have a basic knowledge of the main problems facing collections of historic photographs;
have an awareness of the different types of photographs and their different deterioration patterns;
know about appropriate storage and display techniques to ensure the preservation of photographic collections; and
be able to manage photographic collections in your care, so that access to the collections is assured while at the same time the collections receive maximum protection.
Introduction
Since its invention in 1839, photography has enjoyed enormous success. It has gone from being something quite rare and mysterious to something quite everyday—commonplace. Unfortunately, because photographs are everyday items we don’t always give them the care that they need.
All photographs, both old and new, require special care. Many photographs, including modern colour photographs, are unstable, and will fade rapidly if they are not processed properly in the first place, if we display them for long periods and if we do not store them appropriately. In some cases, this can result in the complete loss of the photograph.
Compromise is nearly always necessary when trying to find a balance between using and preserving collections. However, there is much that can be done to preserve the photographs in your care, through careful and thoughtful handling, storage and display.
Types of photographs
There is a huge range of different types of photographs. These sections on keeping photographs apply, among others, to:
- daguerreotypes;
- colour photographs;
- salted paper prints;
- cyanotypes;
- collodion prints;
- silver-gelatine prints;
- safety film negatives;
- glass plate negatives;
- modern colour prints on resin-coated papers
- ambrotypes;
- opaltypes;
- albumen prints;
- carbon prints;
- slides;
- tintypes; and
- Cibachromes;
These types of photographs differ in their components and chemistry, and the base on which the photograph is produced.
What are the most common types of damage?
Probably the most obvious damage you will see is physical damage. This includes problems such as:
tears;
creases. These almost always cause tiny splits or fractures in the emulsion;
dog-eared corners. These also cause tiny splits or fractures in the emulsion layer;
insect attack. The materials used to make photographic emulsions are a good food source for some insects. Insects, mice and rats will also eat the paper base of photographs;
abrasion and scratching. Photographic emulsions are made from materials such as gelatine and albumen—egg white. These materials form very smooth films, which are very easily scratched when rubbing against other photographs and rough paper surfaces such as album pages;
indentations in the photograph where labels have been written or typed directly onto the back of the photograph. If excessive pressure has been applied, the emulsion can be fractured; and
emulsion peeling away from the paper base.
The other most obvious damage is the result of chemical deterioration:
- fading of the photographic image, accompanied by loss of detail;
- yellowing of the image. In many historic black and white photographic processes, the image becomes warmer in tone and changes from blacks, whites and greys to browns and yellows;
- colour change and fading of colour prints, negatives and slides. Colour prints are most susceptible to this type of damage;
- silver mirroring—silvering out—in shadow areas. This is such a common symptom that nearly all 19th century gelatine developing- out prints are affected;
- staining. Stains can develop on photographs. Some come from within the photographs and others from the materials that are in contact with the photographs, such as album pages and sticky tape; and
photographs which have broken or fractured emulsion are more susceptible to chemical deterioration.
Common causes of damage
All the most common types of damage are caused by:
poor handling;
poor storage methods;
inappropriate display methods;
chemical changes in the photograph;
chemical changes caused by chemicals that are present in materials in contact with the photographs; and
a combination of any or all of the above.
The following sections will outline practical steps you can take to minimise damage.
The do\'s and don\'ts of handling photographs
Handling photographs with care and commonsense helps prevent damage. Because photographs are highly susceptible to physical damage from improper and frequent handling, you should handle them as little as possible.
When you must handle them, make sure your hands are clean. You can wear gloves for added protection—cotton gloves are often recommended—but they are not always appropriate because they can make it much harder to pick up individual photographs. Clean, close- fitting, surgical gloves are a good alternative to cotton gloves.
Old photographs can be very brittle, particularly if they already have tears and creases. So it is important to give them proper support when handling them. New photographs also need support so that they are not damaged.
If you must pick up a photograph to examine it closely, it is better to place it on a rigid support, like a piece of cardboard, and lift the board.
Holding a photograph in your hand can make it curl and involves greater risks of damage. If you must carry photographs over any distance, they should be carried horizontally and supported on a rigid support, like a piece of cardboard. Even if photographs are mounted on cardboard, don’t tuck them under your arm to carry them. They should be supported as described above. Many old photographs were mounted on board which becomes very brittle over time. If these boards break, the photographs attached will break as well. Placing them in folders, Mylar pockets, Copysafe sleeves or polyethylene bags provides added protection.
Photographic emulsions are easily scratched and need to be protected when you are handling more than one photograph at a time. You can protect them by separating them or interleaving them, ideally with archival materials such as photographic storage paper, Mylar and acid-free glassine. For short-term interleaving, silicon release paper or other papers with a very smooth surface can be used.
CAUTION:
Papers which are very opaque, white and have a very smooth almost shiny surface are not suitable for interleaving. These papers are called coated papers and have a finely ground, mineral coating. When they are wet they become very sticky.
Make prints of frequently-used photographs. The copy prints can be used as the working records, instead of the originals; and the negative can be used to produce new copies when the first ones wear out. The original photographs can be stored safely.
The do\'s and don\'ts of labelling and repair
Inappropriate labelling and repair methods can damage photographs. The following guidelines can help prevent damage.
Biros, other ink pens and markers should not be used to label photographic prints. Many of these inks, particularly felt tip pen inks, can spread and cause unsightly staining.
When it is necessary to label a photographic print, write in soft pencil—a B pencil is good—on the edge of the back of the print. Don’t apply pressure because this can leave indents in the photograph and can fracture the emulsion.
Sometimes it is necessary to label negatives. This must be done with extreme care. It is best to use a permanent ink, such as Indian ink. The information should be recorded on the very edge of the negative, outside the image area. It is very difficult to write on the shiny side of the negative, so write on the duller side: this is the emulsion side of the film.
Paper clips, even plastic ones, can damage and distort photographs. They should not be used for attaching labels, even temporary ones, to photographs. If you need to place a temporary label with a photograph, write it on a piece of paper large enough to fold around the whole photograph.
Do not mend photographs using self-adhesive sticky tapes of any kind.
These tapes go through a number of stages when they deteriorate. Firstly, the adhesive becomes very sticky and will be absorbed easily into paper, fabrics and emulsions. In the next stage, the adhesive changes chemically and begins to yellow and eventually turns a dark orange. At this stage the adhesive is almost totally insoluble and the stains cannot be removed.
If you have a damaged photograph, place it in a protective sleeve or wrapper, to prevent further damage until you can get advice from a conservator.
Never use adhesives such as rubber cement with photographs. It ages in the same way as sticky tape adhesives and contains sulphur. Sulphur reacts chemically with photographs, which are made up of silver particles.
Storing photographs
Adverse storage conditions affect all items in a collection. The effects are not always dramatically obvious. Changes occur gradually over a long period of time. However, once the changes have occurred they are often irreversible, or involve complex and costly treatment.
A good storage environment can prevent physical damage, help slow down chemical deterioration, and greatly increase the life of photographs. The following sections outline:
the ideal conditions for storing photographs;
general storage guidelines;
the best materials to use for storing photographs;
practical steps you can take to improve your photographic storage, even when conditions are not ideal; and
some easy, do-it-yourself methods for storing photographs.
Ideal conditions for storing photographs
Ideally, photographs should be stored in an environment where:
Temperature is kept low. The level recommended by Kodak for storing 19th century photographs
is 15°C. As this is difficult to achieve at home and in most working environments, a more realistic level has been set at 18°C. Daily fluctuations in temperature should be no more than 4°C. In some areas, this is extremely difficult to achieve.
Relative humidity is in the moderate range of 30–50%RH. The control of relative humidity is very important when storing photographs. Within the 30–50%RH range, conditions are dry enough to inhibit chemical reactions and the growth of mould; but it is also moist enough for paper and photographic emulsions to remain flexible.
Fluctuations in relative humidity should be kept to a minimum. This is important because the paper and emulsion components of photographs react at different rates to changes in relative humidity.
With extremes or rapid fluctuations in relative humidity, the paper and gelatine layers can pull away from one another.
For more information
For more information about temperature and relative humidity, please see Damage and Decay.
Light is kept to a minimum. Light is required only when the photographs must be viewed: for example, when they are on display, being accessioned or being used for research. Information about appropriate lighting levels are given in the section Ideal Conditions for the Display of Photographs.
Photographs are protected from pollutants, dust and insects.
For more information
For more information about the damaging effects of light, dust, pollutants and insects please see Damage and Decay.
General storage guidelines
Careful consideration should be given to the storage site and the storage systems. In situations where you are can achieve the ideal conditions, a good storage system in an appropriate storage site gives added protection to your collection. If the available facilities or the local climate make it difficult for you to achieve the ideal conditions, the selection of the storage site and the storage system you use become even more critical in preventing damage to the collections.
The following notes are guidelines for selecting storage sites, and outline the principles to be followed for protecting your collections in storage.
The storage site should be in a central area of the building where it is buffered from the extremes of climatic fluctuations which can occur near external walls, in basements and in attics. Don’t store photographs in sheds.
The storage site should not have any water, drain or steam pipes, particularly at ceiling level. Leaking pipes can cause a lot of damage. Storage systems should be easy to use and accessible. Ease of use and accessibility usually mean that things will get less damaged during handling. Frustration with a difficult system can lead to damage.
Standard-size photographs, glass negatives and magic lantern slides should be stored vertically. This makes sorting through the collection to find things much easier than if they are stacked one on top of the other. It also avoids the situation where one photograph has to carry the weight of those stacked on top of it.
Flat storage is preferred for larger photographs because they don’t have the rigidity to support their own weight in vertical storage. If they are stored vertically they will tend to bow.
CAUTION:
It is undesirable to stack a large number
of photographs one on top of the other. The items on the bottom of the stack would have to take the weight of those above. If they were stored in high humidity conditions, the emulsion could become sticky, and the photographs on the bottom of the stack would stick to their wrappers or interleaving sheets.
Dividers or secondary boxes should be placed within storage boxes or filing cabinets. Dividers reduce the movement of items within the storage system, and provide additional support to the stored items.
Layers of storage should be provided. This gives maximum protection from:
- fluctuations in relative humidity and temperature. This is especially important in areas where the ideal levels of relative humidity and temperature cannot be achieved—the multiple layers of storage act as a buffer zone between the photographs and the extreme or fluctuating conditions;
- dust, pollutants and insects; and
- the damaging effects of light.
Each photograph should have its own protective wrapper or enclosure to protect it. Further layers of protection should be provided. Individually wrapped photographs should be boxed.
Labels should be provided on the outside of storage and housing systems, so that items can be located easily without having to search through and inspect every similar item.
For more information
Instructions for making a four-flap wrapper for photographic storage are given in the section Easy do-it-yourself Methods for Storing Photographs, later in this section.
The best materials to use for storing and displaying photographs
There are many materials which provide a very safe and protective storage environment for photographs. There are also materials which should not be used because they can accelerate the deterioration of photographs. The list below summarises the good and bad materials.
GOOD
metal furniture with baked enamel finish
photographic, museum or conservation-quality mount board
photographic storage paper
plastics such as archival-quality polyester and polypropylene
photographic-quality rag and wood pulp papers
BAD
furniture made from uncured wood or recently painted furniture
PVC (polyvinylchloride) a common plastic
coloured papers and coated papers
black papers and boards—these often contain sulphur
poor-quality papers such as newsprint or butchers’ paper
Wrappers, enclosures and mounts—anything which is in direct contact with the photographs—should be made from materials which are chemically inert, that is, they will not cause chemical damage to the photograph. Nor should the wrappers, enclosures and mounts cause physical damage.
Preferred papers and boards for photographic storage are those made from cotton or linen, or wood-pulp papers which have been treated to remove harmful chemicals. These papers are considered to be photographic-quality storage papers, and are available from conservation material suppliers. Research shows that papers containing alkaline buffering, which are used widely for storing archives and works of art on paper, should not be in direct contact with photographs, but can be used for outer storage layers.
Plastics used widely for photographic storage are archival-quality polyester films such as Mylar D and polypropylene. Mylar is clearer and offers more support to the photographs than polypropylene. Polypropylene is cheaper and readily available. Copysafe sleeves are suitable polypropylene enclosures. Tyvek, a spun, bonded polyethylene is also suitable for wrappers for photographs.
CAUTION:
Plastics can severely limit air flow around photographs and this can lead to mould growth and sticky emulsion.
Abrasion is a major problem for photographic emulsions, especially for gelatine. Therefore, the material which is in direct contact with the emulsion must be very smooth and slick, like the surface of the photograph. An already abraded photographic emulsion will abrade Mylar and photographic storage paper.
Boxes should be made from good-quality materials. If non-archival boxes are to be used they should be lined with a good-quality paper or board.
Ideally, storage furniture should be metal, with a baked enamel finish. Wood gives out active chemicals, sometimes for many years. Wood polishes and varnishes also contain substances which can damage photographs.
Materials to avoid are:
- poor-quality papers. Many poor-quality papers become acidic over time. Acids attack the paper fibres, causing the paper to become brittle and crumbly. Acids from these papers can migrate to the photographs and cause damage to the emulsion, the photographic image and the paper base. Ordinary cardboard boxes and film boxes are not recommended for storing photographs for the same reasons;
- sulphur-containing materials. Remember that sulphur tarnishes silver, and photographs are silver-based. Avoid any papers and boards which may contain sulphur. Even good-quality wood-pulp papers contain sulphur. Black dyes used to colour black paper often contain sulphur. Rubber cements and rubber bands also contain sulphur and should be avoided; and
- plastics. Never store photographs in plastics such as polyvinyl chloride—PVC. The PVC in folders and storage sleeves breaks down in the presence of atmospheric moisture, to produce hydrochloric acid. This is a strong acid which will cause irreversible damage to your collections.
Practical steps you can take to improve your photographic storage
Housekeeping is important; storage areas should be kept clean and inspected regularly for mould and insect activity.
Cleaning materials containing chlorine bleaches or ammonia should not be used near photographic collections. Neither should naphthalene, insecticides and fungicides. These are active chemicals which could adversely affect photographs, especially in an enclosed storage environment.
Layers of storage should be provided, with each photograph having its own individual wrapper wherever possible. If you are storing photographs flat, take care not to stack too many individual items on top of others; heavier and larger items should be placed on the bottom of the stack.
Don’t store photographs in boxes on the floor. And also take care not to stack too many storage boxes on top of each other. This can make access difficult, damage the collections and increases the risk of injury.
Individually wrapped photographs should be boxed. If you are purchasing storage boxes for your collections, consider buying clamshell or drop-back boxes. These are the same style as Solander boxes and are the preferred design because they allow easy access to all items.
There are a number of other photographic storage systems, which are available from suppliers of conservation materials.
If you are not able to buy new boxes, you can modify your existing boxes, or use ordinary cardboard boxes and film boxes. These are not ideal, but can be upgraded by lining them with polypropylene, polyester or a good-quality rag paper. You can also seal them with acrylic varnish or acid-free polyvinyl acetate—PVA—but remember that the sealant must be allowed to cure for at least two weeks. Alternatively, you could make your own boxes.
For more information
For instructions on making acid-free storage boxes, please see the chapter on Books in Cultural Material.
Instructions for making a four-flap wrapper for photographic storage are given in the section Easy do-it-yourself Methods for Storing Photographs, later in this chapter.
Framed photographs
The glass, frame and mat should be clean. Inspect each item for insects and mould before storing it. Remove the screw-eyes and wire from the frames, because they can scratch and damage other items they come into contact with.
Wrap each framed work in acid-free paper or Tyvek, to protect it from dust and reduce the risk of insect attack, and place it upright in a sturdy box.
Group items according to size; when the sizes vary greatly, place a cardboard spacer between the dissimilar frames. If different sizes are mixed, frames can become distorted and can damage each other.
Mounted or matted photographs
Window mounts provide some protection. However, the surface of each photograph should be protected by covering it with an acid-free, non- buffered, interleaving paper, or by wrapping the mounted photograph in a four-flap wrapper.
Mounted photographs can be stacked flat, but numbers should be limited to five items per stack. The larger the photographs the fewer should be stacked: the weight of stacked items can damage the image layer of the items at the bottom.
Don’t stack photographs if you have problems with high or fluctuating humidity. The emulsion could become damp and the weight of other photographs could cause the wrapper to stick to the emulsion. Loosely packed, vertical storage is preferred.
Group the photographs according to size.
Don’t overfill storage boxes. The boxes should be of an appropriate size to allow easy access, but also to minimise movement of items within the box.
If a box is not full, the photographs may bend. The empty space can be filled by placing a sandwich of two museum-quality mount boards with acid-free tissue filler in the box.
When moving the photographs, and if storing upright, maintain the correct orientation of the photographs. If mounted correctly, the photographs will be hinged at the top. Maintaining the correct orientation ensures that the hinges are not placed under unnecessary strain.
Loose photographs
As far as possible loose photographs should be stored according to the storage principles outlined above.
Wherever possible wrap each photograph in a four- flap wrapper made from good-quality materials such as photographic storage paper.
If individual wrappers or enclosures are not possible, the photographs should be interleaved with acid-free non-buffered paper and stored in boxes. Movement within the boxes should be minimised. If a box is not full, the photographs can bend and crease, corners can break and they can tear.
Albums are another alternative for storing loose photographs. Loose photographs can be kept in archival-quality photograph albums. It is important to note that most commercially available albums are not of archival quality.
Cased photographs
Each daguerreotype and ambrotype usually has its own protective case; and these cases are largely responsible for their preservation. The cases are an important part of the object and should be protected and kept clean.
Each case should be wrapped, or have a dust cover made to fit. Cased photographs can be stored in an appropriately sized box or four-flap wrapper made from good-quality materials.
Photographic negatives and slides
Store negatives in acid-free paper negative holders or in polypropylene negative sleeves in ring binders.
Slides can be stored in metal slide files, carousels or trays, covered to keep out dust. Sleeves are available for storing slides in filing cabinets. If the sleeves are of good-quality materials and hold the slides securely, this method is effective. It is important not to overfill the filing cabinet drawers. Easy access leads to better handling.
Plastic sleeves are not recommended in situations where there are problems with high or fluctuating humidity. Plastic sleeves restrict air flow and they can stick to moist emulsion.
Glass negatives and magic lantern slides
Each negative or magic lantern slide should be in its own four-flap wrapper made from good-quality materials such as photographic storage paper.
Storage boxes need to be strong and rigid—to give maximum protection to the glass.
A collection of glass negatives or slides is quite heavy and the storage box must maintain its rigidity when lifted. As the glass is heavy, consider splitting your collection into a number of boxes, rather than putting them all into one. This will protect your collection and be much easier on the people who have to retrieve or carry the boxes.
Line the bottom and sides of storage boxes with Plastazote, a polyethylene foam. This material absorbs impact and helps protect the fragile glass negatives and slides.
The negatives and slides, in their wrappers, should fit snugly into the box—to minimise movement.
Store the slides or negatives vertically in the storage box. Place a piece of Plastazote about every ten slides-to absorb any impact and to minimise movement.
Group the slides and negatives according to their size.
Opaltypes
Opaltypes are photographs on opaque glass and are 100 years old. Remember that this old glass is very brittle and the slightest bend will cause a break.
Opaltypes need a rigid support system.
The support system is made up of a rigid backing, with rigid side strips at the top, bottom and sides.
Gator foam, thick plywood—sealed—or thick Masonite are all suitable. Acids are not a problem with opaltypes; but they are photographs, so take care to avoid sulphur-containing materials.
Easy do-it-yourself methods for storing photographs
This section describes:
- methods for protecting individual photographs;
methods for attaching photographs to album pages so that they can be easily removed without damage; and
methods for constructing simple albums.
Photographs should be wrapped individually or interleaved if possible. This protects the individual photographs from abrasion, dust and light, and provides the basic layer in a layered storage system.
Making a four-flap wrapper
Mark out with pencil the four-flap wrapper on the material you are using to store individual items.
The base of the four-flap wrapper should be slightly bigger than the item, so that the flaps can fold over without bending the edges of the photograph, but not so big that the photograph can move freely within the wrapper.
The flaps are marked out slightly shorter than the base, and tapered from the base to the outside edge—this is not shown in the diagram.
When making a wrapper for thicker items, for example, glass negatives or slides, allow for the thickness or the wrapper will not fit.
Once it is marked out, the wrapper can be cut and the flaps folded over. The dotted line indicates where the wrapper is folded.
The photographic emulsion should be placed face- down on the base, and the flaps folded around the back of the item.
Simple wrapper/interleaving method
There are occasions when a simpler wrapper may be more practical. In this case, you can place the individual photographs inside a fold of the material you are using for storage. This method is better than simple interleaving.
Preferred methods of attaching photographs to album pages
Photocorners: Photocorners are an excellent method of attaching paper items to mounts without using adhesives. They should be made from archival materials—Mylar is particularly suitable.
Cut a strip of Mylar to an appropriate size—15 x 45mm is a good size for small items. Then fold the strip to produce a triangular section in the centre, as illustrated:
Mylar is difficult to fold and you may need to use a letter opener, a bone folder or the blunt edge of a knife to crease it fully.
Once this is done, place 6mm wide acid-free double-sided tape on the unfolded ends of the photocorner.
This way, the photocorner can be stuck down to the backing paper and no adhesive touches the items being mounted.
Slits in the album pages: This technique can also be used for attaching photographs to album pages. Using a double slit, as illustrated, involves much less risk to the photographs than a single slit.
CAUTION:
This method should be used only with paper and should be considered as a last resort, because the corners of the photographs can be creased and eventually break along the line of the slit in the paper backing. This method should never be used with heavy paper or cardboard.
Simple albums
If archival-quality albums are unavailable or unsuitable, or if you would prefer to make your own, you can make an album using a ring binder.
The photographs should be attached to thin acid- free card or medium-weight, acid-free paper by one of the methods outlined above. If you are using the slits in the album pages method of attachment, use paper not card. If you don’t have acid-free paper, you can use fresh photocopy paper, but consider this an interim measure only.
Place the photographs on their supporting papers or card in Mylar or Copysafe polypropylene sleeves, which are positioned in the ring binder.
If the albums are to be kept in storage, they should be placed in boxes or wrapped, to prevent dust entering the sleeves.
A word of caution about buying albums
Many commercially available photographic albums are not suitable for the long-term storage of photographic collections. Damage to collections can result from the use of some albums. This section describes some of the factors you need to be wary of.
So-called magnetic albums. Photographs are held in position by placing them on top of parallel lines of pressure-sensitive adhesive on the surface of the album pages. A plastic sheet is then placed over the top of the page containing the photograph.
Pressure-sensitive adhesives are the same as those used on sticky tapes. As these adhesives age, they first become very sticky and are absorbed easily into paper, fabrics and emulsions. In the next stage the adhesive changes chemically and begins to yellow and eventually turns a dark orange.
At this stage the adhesive is almost totally insoluble; and the stains, and sometimes the photographs, cannot be removed. Photographs and papers attached to these album pages develop stripes.
The rigid, cardboard pages of these albums are made from poor-quality paper, which becomes acidic as it ages.
The plastic sheets which cover the pages and photographs are often made from PVC or another plastic which contains chlorine. Remember that PVC can break down in the presence of atmospheric moisture and produce hydrochloric acid. This is a strong acid which will cause irreversible damage to your collections.
The plastic covers on these albums are not archival-quality, and in some cases may be PVC.
Any album with plastic sleeves or plastic covers. There are tests which can be carried out to identify PVC; but they are destructive and will make you unpopular with shop owners. Instead, try smelling the album; if you detect a strong smell it could be PVC and should be avoided for use in long-term storage.
Black paper album pages. Many photograph albums have black pages; but remember that black dyes can contain sulphur which reacts irreversibly with silver and can change images. If you are looking for something for long-term storage, try to find out if the albums are archival-quality.
Displaying photographs
Photographs on display can be affected by adverse conditions, just as they are when they are in storage. During display, however, there are added factors which can contribute to the deterioration of collections. These differences will be discussed in the following sections which deal with:
how light affects photographs;
the ideal conditions for displaying photographs;
lighting hints;
mounting and framing photographs;
some easy do-it-yourself methods for displaying photographs; and
the best materials to use for displaying photographs.
How does light affect photographs?
Light is essential in a display environment. But light, especially when it is accompanied by UV radiation, can cause extreme and irreversible damage to many types of photographs. Many components of photographs are adversely affected by light and UV radiation.
Paper can become brittle and yellow, especially if it contains lignin.
Proteins, such as albumen and gelatine emulsions are affected: albumen yellows and gelatine breaks down.
The dyes used in colour photographs fade when exposed to light. Dyes used for tinting many 19th century photographic prints fade very quickly because early synthetic dyes had very poor light- fastness.
The worst reaction for historic black-and-white photographic prints on paper is the photochemical breakdown of lignin, contained in some papers. This reaction produces peroxides, which are strong oxidising agents and chemically attack the silver image.
Exposure to light can multiply the adverse effects of poor environmental conditions. Remember that damage caused by light is often accelerated by high relative humidity and temperature.
For more information
For more information about the damage caused by light and UV radiation, please see Damage and Decay.
Ideal conditions for the display of photographs
Photographs should be displayed in similar conditions to those outlined for their storage; however, there are some differences.
Light is essential in a display environment, but must be set at levels which will not adversely affect the collection. Original historic photographs and colour prints should be considered sensitive to light. Therefore:
the brightness of the light should be less than 50 lux; and
the UV content of light should be less than 30μW/lm and no greater than 75μW/lm.
Copy photographs and Cibachromes can be illuminated at higher levels.
CAUTION:
All damage caused by photochemical reactions is cumulative and irreversible.
For more information
For more information about measuring the brightness of light and UV content of light, please see Damage and Decay.
The ideal storage temperature for photographs is quite low and is often thought to be too cold for the comfort of people visiting or working in the museum, gallery or library. Therefore the compromise temperature for the display of photographs has been set at 21°C.
Relative humidity is in the moderate range of 30–50%RH, with fluctuations kept to a minimum, as for storage.
The control of relative humidity in a display area may be more difficult than in a storage area. Fluctuations in relative humidity are more likely, because of the varying numbers of people visiting the display followed by no people at times when the display is closed.
The emphasis should be on providing a buffer zone between the photographs and the extreme or fluctuating conditions. Display cases and frames provide layers of protection from extreme or fluctuating conditions.
Protect photographs on display from pollutants, dust and insects.
It is important to use appropriate materials and methods when displaying photographs: to ensure the long-term preservation of the collections.
Lighting hints
Photographs are made up of a number of different materials, and lighting levels for display must take into account all those materials. This is why most photographs are considered to be sensitive to light.
As light can be so damaging to photographs it is important to consider carefully the lighting of displays. This section provides some hints of how to minimise damage to items lit for display.
Tungsten incandescent bulbs are the best form of lighting for the display of photographs because they give out very little UV radiation.
Keep the brightness or intensity of the light low, and regulate exposure periods. Less exposure to visible light and the elimination of UV radiation helps prolong the life of photographs.
When displaying photographs, remember that light also affects the paper on which the photographs are printed—except for particular types of photographs such as opaltypes, which are on glass. Single-layer and two-layer photographs should be displayed in lower lighting levels than those with a three-layer structure. The baryta layer in the three-layer structure protects the paper support and there is less likelihood of photochemical damage to the paper.
Never display original salted paper prints. They are extremely light-sensitive and can fade badly.
It is recommended that copies be displayed, rather than the originals.
Framing and mounting photographs for display
Mounting and framing photographs supports and protects them from extreme or fluctuating environmental conditions, as well as enhancing their appearance.
Mounts/mats
Window mounts/mats prevent direct contact between the surface of the photograph and the glazing. They are also used for aesthetic reasons, providing a border for the image.
It is important to separate the glazing from the photograph because:
sudden temperature changes can cause condensation on the inner surface of glass;
if the photograph does not have a window mount, the emulsion can become sticky and stick to the glass; and
if photographs stick to glass and then dry off, they are extremely difficult and sometimes impossible to separate without damaging the image.
Photographs should be hinged and mounted in the same way as works on flat paper.
If there is enough margin at the edge of the photograph, you can use photocorners to attach the photograph to the mount. This will be easier with modern, colour photographs because many water-based adhesives will not stick easily to resin-coated paper.
If you don’t have the equipment to cut window mounts, contact your local framer, who should be able to cut the window for you.
If you are having items mounted and framed by a framer, specify conservation mounting and framing and conservation-grade materials. Not all framers have conservation-grade materials in stock, so give them enough time to order the materials in.
If you would prefer not to have a window mount/mat framing the image, some provision should be made to separate the photograph from the glazing once it is framed. This is usually done with spacers. These can be made with strips of mount board stuck to the inside of the rebate of the frame. They should be cut thin so that they are not visible.
Frames
Frames add to the aesthetic appeal of photographs and provide a solid, protective outer layer for the photographs they contain. This is particularly important if you are dealing with a travelling exhibition; in this case the frames are not only protective but are also much easier to handle than unframed photographs.
Conservation framing is more complex and more expensive than standard framing techniques, but it is the best protection for your collection while it is on display, especially if the photographs are to stay framed for a long time and are part of a travelling exhibition.
There are a number of components in the conservation framing system.
The moulding is usually referred to as the frame. Different types of framing materials will be discussed further in the section The best materials to use for the display of photographs.
Glazing should provide physical protection to the photograph with a minimum of distraction to viewing. Glass or acrylic sheeting can be used for glazing. Each has advantages and disadvantages:
glass can break and damage the photograph. It has a slight colour, either a blue or green, which may interfere with the colour-balance in the photograph. This colour becomes more noticeable as the glass ages; and
acrylic sheeting, such as Perspex or Plexiglas, is prone to scratching, which can be visually disturbing. It can also develop a strong static charge. But acrylic sheeting gives better protection against UV radiation than glass, particularly if a UV-absorbing acrylic is used.
The glazing seal—shown as a rightangle in the diagram—is applied around the edges of the glazing to the rebate of the frame. It stops insects and airborne pollutants from entering through the front of the frame. It also protects the photograph from any chips of glass which may come away from the cut edge of the glass.
Glazing seals are not used universally in conservation framing systems—some argue that they reduce the rate of air interchange between the frame and the outside world.
The moisture barrier—an inert material—for example, Mylar or aluminium foil attached at the back of the frame, reduces moisture migration into the frame. Creating this barrier is important when framing items which are particularly sensitive to moisture: Cibachromes, for example. The moisture barrier is shown between the brad and the gummed paper tape.
The outer tape seal, from the edge of the moisture barrier to the edge of the frame, completely seals the package and stops insects and air pollutants entering the framing system.
Easy do-it-yourself methods for displaying photographs
It is not always appropriate to go to the expense and effort to frame your photographs for display, especially if they are to be displayed only for a short time. But it is still important to provide protection and support for the photographs. Some alternatives to mounting/matting and framing are:
displaying your photographs in their polyester or polypropylene storage sleeves; and
placing the photographs in their storage sleeves in a mount.
With these two methods, you can place the photographs in a display case or attach them to a display board. When attaching them to a display board, make sure:
the method of fixing the items to the board is secure and will not allow the photographs to fall; and
it must not damage the photographs or their permanent storage enclosure. For example, pushing pins through the storage sleeves is not recommended, while using double-sided tape on the outside of the storage sleeves would not cause any lasting damage and would be easy to remove if the exhibition was a short one.
When attaching the photographs to a solid support, such as a sheet of conservation mount board cut to an appropriate size, the methods described in the section on storage can be used. Once the photograph is supported adequately, it can be placed in a display case. The solid support performs a number of functions:
- it supports the photograph during handling, that is, when it is being placed in or removed from the display case; and
- it acts as a barrier between the materials of the display case and the photograph.
The best materials to use for displaying photographs
As already discussed in the section on storage, some materials can have an adverse effect on photographs. It is important to select carefully the materials which you are going to use in your display system.
Wrappers, enclosures, mounts and anything which is in direct contact with the photographs should be made from materials that are chemically inert and which will not cause physical damage to the photographs.
Mount/matboard should be conservation-grade: either a 100% rag board or purified wood-pulp— alpha cellulose. These boards have had the lignin and other contaminants removed.
Black-and-white gelatine emulsion photographs can be mounted/matted with board which has a 2% alkaline buffering. Whether a board is buffered or not will be noted in the manufacturer’s specification.
Colour prints and cyanotypes should not be mounted on boards which contain alkaline buffers; a photographic-quality mount/mat board would be suitable for these photographs.
CAUTION:
Colour prints may be affected by the presence of alkalis, and should be mounted on non-buffered, acid-free board. The cyanotype is another photographic medium definitely known to discolour in the presence of alkaline buffering materials.
The two most common framing materials are metal and wood.
Metal frames—aluminium section—are ideal for framing photographs because they are:
physically strong;
chemically inert, giving off no destructive vapours;
unaffected by decay, insect or fungal attack;
the assembly hardware allows them to be opened easily for inspection; and
the clean, simple mouldings present most photographs to their best advantage.
Wooden frames often look very impressive, especially on historic photographs. But they have characteristics which could make them unsuitable on preservation grounds:
raw wood gives off peroxides, which are strong oxidising agents and harmful to prints; and
softwoods, like pine and cedar, contain resins which remain volatile for years and will affect prints adversely.
Basswood and Jelutone are low-resin woods and are considered suitable for preservation-grade frames.
If you are using wooden frames, the rebate should be sealed with polyurethane or acrylic resin varnish to prevent acid vapours from the resins reaching the prints. And remember that even hardwoods contain some resins.
Frames which have been sealed as outlined above, stained or painted should never be used until the paint has cured thoroughly. Dry, but uncured, paint emits vapours known to be particularly harmful to photographic emulsions.
Tapes suitable for use as glazing seals are Filmoplast P90, Tyvek tape, 3M Scotch 810 magic transparent tape and polyester tape 8411.
Tapes suitable for use as outer seal tapes are gummed paper tape, Tyvek tape, 3M Scotch 810 magic transparent tape and polyester tape 8411.
Mylar is suitable for use as a moisture barrier in a conservation framing system and as a storage and display sleeve.
Polypropylene can be used as a display sleeve; but it is not as clear as Mylar and does not look as attractive.
GOOD
metal furniture with baked enamel finish
photographic, museum or conservation-quality mount board
photographic storage paper
plastics such as archival-quality polyester and polypropylene
photographic-quality rag and wood pulp papers
BAD
furniture made from uncured wood or recently painted furniture
PVC—polyvinyl— a common plastic
coloured papers and coated papers
black papers and boards—these often contain sulphur
poor-quality papers such as newsprint or butchers paper
Summary of conditions for storage and display
____________________________Storage_______________Display______________
Temperature
18oC ± 4°C
21oC ± 4oC
Relative Humidity
30–50% RH
30–50%RH
Brightness of the Light
Dark storage preferred
Less than 250 lux.
UV Content of Light
Nil
Less than 30 μW/lm and no greater than 75 μW/lm.
Photographs in Australia’s climatic zones
The climatic zones outlined below are broad categories. Conditions may vary within these categories, depending on the state of repair of your building and whether or not the building is air conditioned.
Arid
This climate is generally very dry, however, in arid areas it is often very hot during the day and very cold at night. This wide fluctuation in temperature is matched by wide fluctuations in relative humidity, for example from 75%–20%RH in a day.
When caring for photographs in arid areas it is important to note that:
insects can still survive;
paper and photographic emulsions tend to give out the water they contain - this can lead to the photographs becoming dry and brittle; and
as they release moisture at different rates, the paper and emulsion can begin to separate.
Remember that even arid areas can have periods of higher relative humidity, even though the periods may only be very short.
The system of layers of storage—wrappers, boxes, boxes within cupboards—is particularly suited to arid areas because of the tendency to get quite marked fluctuations in temperature and relative humidity. Many arid areas are also very dusty and so the layers of storage protect the photographs from dust and grit.
Because of the large temperature fluctuations in arid areas, there is a risk that condensation could form inside plastic wrappers, leading to sticky emulsion and possible mould growth.
Note: If your photographic collections have been stored in an arid environment for a considerable period and they are stable—do not try to alter the environment to meet the recommended ideal conditions. This could do more harm than good. The emphasis should be on long term stability.
Temperate
A temperate climate is considered a moderate climate, however, temperate climates tend to have a greater range of temperatures than tropical climates and may include extreme climatic variations.
It is probably easier to come close to the recommended ideal conditions for the storage of photographs in a temperate climate, however, it is unlikely that you will be able to maintain an even environment without the help of sophisticated air conditioning equipment.
The system of layers of storage - wrappers, boxes, boxes within cupboards will be very useful in helping to buffer against the extreme conditions that can occur in a temperate environment.
As for all climatic areas, regular inspection of storage and display areas is important so that developing problems do not go unnoticed.
Note: If your photographic collections have been stored in a temperate environment for a considerable period and they are stable—do not try to alter the environment to meet the recommended ideal conditions. This could do more harm than good. The emphasis should be on long term stability.
Tropical
These climates are characterised by heavy rainfall, high humidity and high temperatures.
When caring for photographs in high humidity conditions it is important to note that:
insects and moulds thrive and reproduce readily.
the rate of deterioration due to light and UV radiation increases.
different components of single objects will take up moisture at different rates and swell by different amounts—this can lead to problems such as emulsions separating from the photographic base paper.
gelatine emulsions on photographs swell and can readily stick to anything they are in direct contact with.
Remember that in tropical areas, air flow is important and this should be taken into account when designing storage and display systems.
The use of plastic sleeves for storage and display is not recommended in tropical areas, as the sleeves restrict air flow and will prevent damp photographs from drying out.
Note: If your photographic collections have been stored in a tropical environment for a considerable period and they are stable—do not try to alter the environment to meet the recommended ideal conditions. This could do more harm than good. The emphasis should be on long term stability.
Summary of conditions for storage and display
Summary of conditions for storage and display | ||
| Storage | Display |
Temperature | 18ºC ± 4ºC | 21ºC ± 4ºC |
Relative Humidity | 30-50% RH | 30-50%RH |
Brightness of the Light | Dark storage preferred | Less than 250 lux. |
UV Content of the Light | Nil | Less than 30 µW/lm and no greater than 75 µW/lm. |
Photographs in Australia\'s climactic zones
Photographs in Australia’s climatic zones
The climatic zones outlined below are broad categories. Conditions may vary within these categories, depending on the state of repair of your building and whether or not the building is air conditioned.
Arid
This climate is generally very dry, however, in arid areas it is often very hot during the day and very cold at night. This wide fluctuation in temperature is matched by wide fluctuations in relative humidity, for example from 75%–20%RH in a day.
When caring for photographs in arid areas it is important to note that:
• insects can still survive;
• paper and photographic emulsions tend to give out the water they contain - this can lead to the photographs becoming dry and brittle; and
• as they release moisture at different rates, the paper and emulsion can begin to separate. Remember that even arid areas can have periods of higher relative humidity, even though the periods may only be very short. The system of layers of storage—wrappers, boxes, boxes within cupboards—is particularly suited to arid areas because of the tendency to get quite marked fluctuations in temperature and relative humidity. Many arid areas are also very dusty and so the layers of storage protect the photographs from dust and grit. Because of the large temperature fluctuations in arid areas, there is a risk that condensation could form inside plastic wrappers, leading to sticky emulsion and possible mould growth. Note: If your photographic collections have been stored in an arid environment for a considerable period and they are stable—do not try to alter the environment to meet the recommended ideal conditions. This could do more harm than good. The emphasis should be on long term stability.
Temperate
A temperate climate is considered a moderate climate, however, temperate climates tend to have a greater range of temperatures than tropical climates and may include extreme climatic variations.
• It is probably easier to come close to the recommended ideal conditions for the storage of photographs in a temperate climate, however, it is unlikely that you will be able to maintain an even environment without the help of sophisticated air conditioning equipment.
• The system of layers of storage - wrappers, boxes, boxes within cupboards will be very useful in helping to buffer against the extreme conditions that can occur in a temperate environment.
• As for all climatic areas, regular inspection of storage and display areas is important so that developing problems do not go unnoticed. Note: If your photographic collections have been stored in a temperate environment for a considerable period and they are stable—do not try to alter the environment to meet the recommended ideal conditions. This could do more harm than good. The emphasis should be on long term stability.
Tropical
These climates are characterised by heavy rainfall, high humidity and high temperatures.
When caring for photographs in high humidity conditions it is important to note that:
• insects and moulds thrive and reproduce readily.
• the rate of deterioration due to light and UV radiation increases.
• different components of single objects will take up moisture at different rates and swell by different amounts—this can lead to problems such as emulsions separating from the photographic base paper.
• gelatine emulsions on photographs swell and can readily stick to anything they are in direct contact with. Remember that in tropical areas, air flow is important and this should be taken into account when designing storage and display systems. The use of plastic sleeves for storage and display is not recommended in tropical areas, as the sleeves restrict air flow and will prevent damp photographs from drying out. Note: If your photographic collections have been stored in a tropical environment for a considerable period and they are stable—do not try to alter the environment to meet the recommended ideal conditions. This could do more harm than good. The emphasis should be on long term stability.
Some miscellaneous advice
Mechanised processing versus hand processing
Modern photographic processing systems cannot guarantee the same long-term stability as hand processing. However, mechanised processing is much cheaper and more convenient.
If the long-term stability of your colour prints is very important to you, it is wise to have them hand processed by a photographer, or to have them processed with a new batch of processing chemicals.
Cibachromes
Cibachromes are very stable, although they are very sensitive to moisture. If you want a very stable colour print, have a glossy Cibachrome print produced from a slide. Pearl Cibachromes are not as stable.
To laminate or not?
Lamination is sometimes promoted as a way to preserve your photographs, but there are problems associated with laminating photographs.
Once a photograph is laminated, it is virtually impossible to remove the lamination material without damaging the photograph and without using strong chemicals.
The process of lamination can damage the emulsion layer of the photograph; and over time the lamination material, with emulsion attached, will pull away from the paper base of the photograph. This damage is permanent.
Lamination may be suitable:
if you have the negative and can print more copies of the photograph; and
you want to protect the photograph in situations where it may get damaged or very dirty.
A reversible alternative is to place it in a Mylar sleeve.
Historic evidence accompanying photographs
Many photographs—particularly older photographs—may come into your collection in their original folder, in a frame or mounted on a card on which the photographer’s name and address are printed.
Often these materials are dirty, deteriorating and not good quality. But they should not be discarded because they often provide valuable information about the photographs.
If the accompanying materials are in very poor condition, lightly brush them clean, then wrap, label and store them separately from the photographs.
From the mid-1850s to the early 1900s, cartes-de- visite and cabinet cards were very popular.
Cartes-de-visite are quite small; cabinet cards, which come in a range of sizes, are larger. Both are made up of photographs stuck down to card. These cards are often poor quality and brittle. Despite their poor quality, these cards should not be removed as they are an integral part of these items. A number of books on the history of photography give further details of these popular photographic formats.
Treatment of damaged photographs is not always simple. It is important when treating a photograph to be able to identify the process before determining the treatment to be applied. It is also important to know:
what materials are likely to have been used. These can vary because many photographers experimented with materials and processes; and
the particular sensitivities of these materials.
A note of warning about nitrate film stock
A number of collections contain examples of nitrate film, which was used for still film and movie film before the introduction of safety film.
Nitrate films are extremely dangerous. They consist of cellulose nitrate, a very unstable material.
As nitrate film degrades, it produces nitrogen oxide. Further degradation results in spontaneous combustion of the film; and because nitrogen oxide reactions produce oxidising agents, this reaction can occur without the presence of oxygen in the air. This means that degraded cellulose nitrate can burn under water or when smothered with fire-retarding foam or sand. Degraded cellulose nitrate is sticky and smelly.
The National Film and Sound Archive conducted a search for nitrate film in Australian collections in the mid-1990s. If you suspect you have cellulose nitrate in your collection, contact the National Film and Sound Archive, or a relevant State institution for information and advice.
A brief overview of the chemistry of photography
Photography—drawing with light—includes any process in which pictures are produced by the action of light on light-sensitive materials.
Light-sensitive materials
Many materials are light-sensitive, but not all are suitable for the production of images:
some materials fade in light;
some materials darken in light;
light causes molecules to decompose in some materials; and
in other materials, light causes molecules to combine and to create larger molecules.
The most commonly used light-sensitive materials in photography are silver salts.
Light-sensitive silver salts
Silver salts decompose in light to produce metallic silver, which makes up the image. The silver salts which were found to be best for this process were the silver halides—silver chloride, silver bromide and silver iodide.
Initially, prolonged exposures were used to develop images. Negatives were placed in a printing-out frame in contact with sensitised positive papers and then exposed to light. Once the images had developed sufficiently, they were fixed chemically. This was the principle of the printing-out papers.
Developers
There are many advantages to be gained from the use of chemical developers. These include:
reduced exposure times;
allowing the photographer much more flexibility in manipulating his/her images; and
making enlargements, reproductions and mass production of images possible.
With the introduction of developers, the sensitised paper was exposed to light for a shorter period. During this exposure time, an invisible latent image formed. This image was then intensified 109 times using the developer.
Developers are reducing agents, that is, they supply electrons to a system.
A number of reducing agents were tried, but not all were successful. If they are too strong they reduce all the silver halide to metallic silver—even the silver halide which has not been exposed to light. If too weak, they will not develop the image enough.
Much of the work done before a suitable process was found was experimentation—to find developers which had enough power to reduce the exposed silver halides, but not enough to reduce those that had not been exposed to light.
Fixers
If photographic images are not fixed, the chemical reactions will continue—leading to loss of image. Once the image has developed, the silver halides which have not been exposed to light must be removed from the system. Fixers are chemicals which dissolve silver halides and remove them from the system.
The fixer and dissolved silver halides must be washed away. Retention of these within the system will lead to discolouration.
Emulsions
Emulsions were produced from:
albumen—egg white;
cellulose nitrate—called collodion in this application; and
gelatine.
Emulsions coated onto the photograph base-paper, glass or metal:
allowed an even spread of the light-sensitive salts over the base material;
provided a smoother surface than the surface of uncoated paper, giving more sharply focused images; and
could be applied in liquid form and then dried in a thin film.
Gelatine
Gelatine survived as the most popular and widespread emulsion material. This is because gelatine has properties which make it particularly suitable for use in photography:
gelatine is soluble in warm water, but remains as a gel in cold water. This allows water- based processing of the image without loss of emulsion. It is important to note that old degraded gelatine may be soluble in cold water;
gelatine can be treated with formaldehyde to harden it, so that it is no longer soluble in hot water;
gelatine contains minute amounts of
materials which increase the sensitivity of the silver halides to light. This is due to the eating habits of cows, which are the source of the gelatine. Cows like hot-tasting food, which contains sulphur. Rabbits, on the other hand, do not like hot food and their gelatine is less suitable.
CAUTION:
While minute traces of sulphur in a properly formulated emulsion can be beneficial, sulphur is not good for photographs because it reacts irreversibly with silver.
A brief overview of photographic deterioration mechanisms
There are two main mechanisms of deterioration: sulphiding and oxidation-reduction deterioration.
Sulphiding
Silver has a strong tendency to react irreversibly with sulphur. The product of this reaction is silver sulphide—a black material that appears yellow when it is in very small particles. The main sources of damaging sulphur are:
- hydrogen sulphide from atmospheric pollution.
- inadequate washing after fixing. It is virtually impossible to remove all the fixer as it is retained tenaciously by paper fibres and baryta coatings. Fixer—sodium thiosulphate—breaks down in the presence of moisture and releases reactive sulphur.
Both of the above cause yellowing, fading and loss of detail in the highlight areas. Eventually the whole image is affected and will fade and change colour.
- use of exhausted fixer baths. Thiosulphates combine with silver ions; many of the resulting molecules are soluble and so the fixer and excess silver can be washed away. If the bath is exhausted, insoluble molecules can form; these are retained by the gelatine. So there are sulphur and silver ions still in the system. The silver reacts to become metallic silver, causing yellowing. Non-image areas change in colour: from white, to yellow then brown.
High relative humidity accelerates sulphiding.
Oxidative-reductive deterioration
This is the most important deterioration mechanism for silver-based images. The main mechanisms and their effects are:
metallic silver particles are oxidised to produce silver ions;
while metallic silver is coloured and therefore makes up the image, silver ions are colourless and do not absorb light;
as ions have an electric charge, they can move around the system. They can migrate to the surface where they are reduced back to metallic silver, creating the characteristic mirroring or silvering out; and
they may also migrate within the system and then be sulphided.
Oxidative-reductive deterioration can also cause loss of highlight detail, overall fading and colour shifts to warmer hues.
Images developed using chemical developers are less vulnerable to this deterioration than those on printing-out papers, because the silver particles in developed images are bigger.
Only minute quantities of oxidising agents are required to cause deterioration and there are many oxidising agents in atmospheric gases and pollutants.
Controlling temperature and relative humidity helps slow down the process.
For more information
For more information about adverse environmental effects, please see Damage and Decay.
Layer structures for various photographs
Single-layer structure, as for salted paper prints, cyanotype, platinotypes. The light- sensitive material is within the paper.
Two-layer structure, as for albumen prints, carbon prints. The light-sensitive material is in the upper emulsion layer. The lower layer is the paper.
Three-layer structure, as for gelatine and collodion printing-out papers and gelatine developing out papers. The light-sensitive material is in the upper emulsion layer. The middle layer is the baryta layer, which gives a very smooth, white surface on which the emulsion layer rests. It is opaque and hides the irregular surface of the paper fibres. The lower layer is the paper.
The structure of modern, resin-coated paper. The centre layer is the paper core. Either side of this is a layer of polyethylene. The light-sensitive gelatine emulsion is on the top. There is also a gelatine backing layer at the base.
A brief history of the development of photography
In a relatively short period photography has grown from a process still in its experimental stages to one that is well established and widely used.
The evolution of photography is not simple and straightforward; it is the result of the efforts of many people working in a great range of disciplines. The following notes give a brief summary of the main contributors and the milestone discoveries.
Beginnings
Well before the beginning of the 19th century, much of the equipment and knowledge necessary for the eventual appearance of photography were available.
The camera obscura had been known since at least 1038, when it was described by Ibn Al-Haitham. It was not until the 17th and 18th centuries that its use became widespread.
The study of photochemistry was a by-product of research into other areas and it was known that:
the action of light alone caused silver salts to darken (Schulze, 1727);
further work, using silver chloride, established that violet light caused silver salts to darken far more rapidly than longer wavelengths of visible light (Scheele). Where it took fifteen seconds for silver chloride to darken when exposed to violet light, it took up to twenty minutes to darken to the same degree when exposed to red light (Senebier, 1782).
silver chloride, which had darkened under the action of light, was insoluble in ammonia. The darkened substance was, in fact, metallic silver (Scheele); and
some resins became insoluble in turpentine after exposure to light (Senebier).
At the beginning of the 19th century, a number of people began to see that it might be possible to obtain a permanent image using the camera obscura and light-sensitive materials.
Thomas Wedgewood and Sir Humphry Davy did some early work on this. They produced images by placing items on sensitised paper and leather and then exposing them to light, but were unable to fix the images.
For more information
For more information about the different wavelengths of light, please see the chapter on Light and Ultraviolet Radiation in Damage and Decay.
The first photograph
In 1816 in France, Nicéphore Niépce produced a negative image using paper sensitised with silver chloride and placed in a camera obscura. But he failed to fix the image.
He produced a permanent image in 1822, using bitumen of Judea, which hardened when exposed to light. An engraving, made transparent with oil, was placed over a glass plate coated in the bitumen. After several hours’ exposure to light, the unexposed areas of bitumen could be dissolved in lavender oil—a light petroleum oil—leaving an image formed by the hardened bitumen of Judea.
In 1827 Nicéphore Niépce became the first person to produce a direct positive photograph from nature. He called the image a heliograph. He had used a bitumen-coated pewter plate which he had placed in a small camera obscura and exposed for about eight hours.
The daguerreotype and the calotype
Photography was announced to the world in 1839. There were two processes employing slightly different manipulations of light-sensitive silver salts.
Daguerre announced his discovery in January 1839 and presented the details of the process to the world in August 1839.
A silver-plated copper sheet was exposed, first to iodine vapour to sensitise it, then to light, and finally to mercury vapour which developed the latent photographic image. The image was then fixed with sodium thiosulphate solution, washed and gently dried over a flame.
The image, a fine amalgam of silver and mercury, had to be protected from abrasion and oxidising agents, and was framed and enclosed in a case.
The daguerreotype was an immediate success, but it had two disadvantages:
it was difficult to see: and,
each daguerreotype was a one-off and could not be used to produce copies.
In 1839 William Henry Fox Talbot prepared his Account of the Art of Photogenic Drawing, or the process by which natural objects may be made to delineate themselves without the aid of the artist’s pencil. This described how he sensitised paper by brushing it with silver nitrate and then sodium chloride. After exposing the paper to light for about two hours in the camera obscura, the image which formed in the paper was fixed using a concentrated sodium chloride solution. By late 1840, Fox Talbot had made significant improvements to his process.
He produced an iodised paper by coating writing paper with silver nitrate solution and then—before it dried—immersing it in potassium iodide solution, thus forming silver iodide in the paper. This paper could be stored for an indefinite period in the dark.
For use, the paper was washed with Fox Talbot’s exciting liquid, then exposed for less than a minute, after which it was brushed again with the exciting liquid. The second application of exciting liquid developed the latent image. The photograph was then washed and fixed. This produced a negative image, which was then waxed to make it transparent.
By exposing sensitised paper in contact with the negative, positive images could be produced. This was the calotype process.
The calotype process formed the base from which modern photography evolved.
Its greatest advantage was that it was a two-stage process. Where previously a negative image had been a disappointment to the experimenter, it was now seen as the means with which to produce multiple positive copies.
Albumen paper and the wet collodion process
By the early 1850s most of the teething troubles of photography had been eliminated; and it was from this time that photography really flourished. In 1850 and 1851 two important improvements to photography were published: the albumen printing- out paper and the wet collodion process.
Albumen printing-out paper was introduced in 1850 and it became the most important print material of the 19th century.
Albumen was prepared by beating egg-white until it was very frothy, and then leaving it to settle to a liquid. Most manufacturers allowed the albumen to ferment, because this improved the final print quality. Very thin rag paper was coated by floating it on top of an albumen and sodium chloride mixture. Before use, the paper had to be sensitised. This was done by floating the paper on a solution of silver nitrate.
For printing, the sensitised paper was placed in a frame in contact with the negative and exposed for periods ranging from a few minutes to a number of hours. Once the image had appeared, it was fixed.
Various improvements were made to albumen paper between 1850 and 1900. These include:
- the introduction of gold toning for use with albumen paper. This changed the image’s colour from a red-brown to a warm purple- brown or blue-black, and improved the stability of the image;
from the late 1880s platinum toning was also used, usually in combination with gold toning: it gave the image a nearly neutral tone. Platinum toning on its own turned the image brown;
from 1863 dyes were added to the paper base to counteract the yellowing of the albumen layer. Pink was the most common dye; but green, blue and violet were also used; and
ready sensitised albumen paper became available in the 1870s. The use of citric acid in the preparation of the paper gave it a shelf-life of several months.
The wet collodion process was announced by Frederick Scott Archer in 1851. This used glass as the carrier for the negative image.
Collodion, containing potassium iodide, was poured over the glass to form a thin, even film. This was immediately sensitised with a silver nitrate solution. The plate had to be exposed while still wet, and then developed with pyrogallic acid.
Sodium thiosulphate or potassium cyanide were used to fix the image, which was then washed and dried. Then the plates were often warmed to receive a protective varnish before any positive prints were made.
It was not an easy process. All the processes described above were done by hand. And if photographs were to be taken outside, a portable darkroom, complete with all chemicals, water and equipment, had to be carried.
Some of the chemicals were toxic, for example, potassium cyanide was used for fixing and for cleaning excess developer off the equipment.
The wet collodion process was extremely popular. The advantages of fine detail, improved tonal ranges and reduced exposure times, plus the fact that the process was not protected by patent, outweighed the disadvantages.
Collodion on glass negatives and albumen-coated paper positive prints were such a successful combination that they dominated photography for over 30 years.
Gelatine dry plates and film negatives
From the 1870s the use of dry gelatine plates became common; and then in the late 1880s film negatives were introduced.
The gelatine dry plate was put forward by Dr R.L. Maddox in 1871. Two years later, ready-coated plates were available.
Glass plates were machine-coated with gelatine containing light-sensitive silver bromide.
The plates did not need any processing to sensitise them before use; they could be stored for many months and required much shorter exposure times than previous methods.
The first film negatives, introduced in the United States in 1888, were made from cellulose nitrate. This was extremely flammable and was gradually phased out in favour of safer film materials.
Collodion and gelatine emulsion papers
Not long after the introduction of collodion and gelatine as emulsions in negative processes, they were applied to paper for the production of positive photographic prints. In these processes the gelatine or collodion emulsions contained the light-sensitive silver salts when they were coated onto the paper. These photographic papers are called emulsion papers.
Collodion printing-out papers became available in 1867. The papers had a barium sulphate layer—the pigment baryta—between the paper and the emulsion, to overcome the problem of the collodion not sticking to the paper. The collodion contained silver chloride and citric acid.
Gelatine printing-out papers became available in the late 1880s.
The only difference between the two types of paper was in the nature of the binder, i.e. collodian or gelatine:
they were both exposed to daylight in printing-out frames and processed in the same way;
they both produced reddish-brown to purple- brown image colours; and
photographs which were double-toned with gold and platinum tended to be neutral. Some papers were self-toning, that is, the necessary salts were contained in the emulsion and were released during fixing.
Most photographic papers after this time had a three-layer structure. The baryta layer produced a very smooth, opaque, white surface on which to coat the emulsion. The image quality was improved as the underlying paper fibres were masked and final image contrast was heightened. The emulsion layer was protected from chemically active substances which might have been present in the paper.
Developing-out papers
Chemical development of positive images was used as early as 1851 by Blanquart Evart in his commercial photographic printing firm. But development was not commonly used until the 1880s, when the materials of the gelatine dry plate method were applied to production of positive prints.
From about 1885, papers coated with gelatine containing silver bromide became available. At first the emulsion was coated directly onto the paper; after 1895 bromide developing-out papers were also coated with a layer of barium sulphate.
Silver bromide and gelatine emulsions were sensitive enough to allow enlargement of negatives.
Bromide developing-out papers produced neutral, black images with improved image stability. This
was largely due to the structure and shape of the silver formed by the development process.
Developed images have much larger silver particles than printed-out images. Chemical development of positive prints produces filamentary silver, which is deposited as long, twisted strands. It is these larger, irregularly shaped silver particles that give neutral-toned images greater chemical stability
In printed-out papers the images are made up of small spherical particles of silver called photolytic silver. The particle size is directly proportional to the amount of light received during exposure. Photolytic silver produced warm-toned images, tending toward reds, browns and yellows. These small particles are very vulnerable to the chemical activity which results in image deterioration.
Chemical development of positive photographic images was the way forward for modern photography. In the first decade of the 20th century developing-out papers began to take over from printing-out papers.
Colour photography
From the early beginnings of photography, there was a desire to produce colour images. But it was some time before any practical systems of colour photography were available and it was many years before colour photography became the norm.
A number of different systems for producing colour images were tried. Many fell by the wayside, while others were altered in minor ways over many years to produce better colour and better quality images.
A full description of the developments is not necessary in such a brief history of photography, so only a few of the developments are listed below. These give some idea of when these developments took place in relation to the development of black and white photography.
In 1903 the Lumière brothers invented and patented the Autochrome process, the first practical system of colour photography. It was a coloured transparent image on glass.
A silver-gelatine emulsion was exposed through a screen of potato starch grains dyed orange, green and violet. After reversal processing, a positive silver image was produced which, when viewed through the colour screen, reproduced the original colours.
Autochrome plates were produced in large quantities between 1907 and 1940.
The Tricolor Carbro—invented in 1905—was used commercially for the first time in 1919. Carbro prints were made by placing three carbon images, coloured with pigment, onto paper. The risk of fading was reduced by the use of pigments instead of dyes.
In 1935 Kodak Kodachrome was introduced. It was first a movie film, then introduced as a 35mm slide film the following year. Other film companies followed with their own colour films.
In 1939 the Diffusion Transfer process was invented. Initially it was intended as a method of rapid document copying. Now it is used in instant- picture cameras.
In 1941 Minicolor prints, made from Kodachrome slides, were made available for the first time.
Kodacolor, a method for producing colour prints from negatives was introduced in 1942.
In 1944, Kodak introduced the Dye Transfer technique. It largely supplanted Tricolor Carbro. It was used primarily by studio photographers or serious artists.
By this time the major hurdles in the development of colour photography had been overcome; from then on, many minor developments were made, resulting in the processes with which we are familiar today.
Identification of historic photographs
The wide range of materials used in producing photographic images has led to a wide range of deterioration patterns. This means that some historic photographs need to be treated differently to others. For example, it is recommended that original albumen prints are not exhibited at all— copies should be made for exhibition. Carbon prints, however, can be exhibited safely if standard exhibition precautions are taken.
Correctly identifying the process is important. In many cases the deterioration pattern can help identify the process used.
Daguerreotype: 1839–c1860
Structure. The daguerreotype consists of a positive image formed by mercury vapour on a highly polished coating of silver on a copper plate. It is usually in its own decorative and protective case.
Appearance of image. The daguerreotype has a silver, mirrored surface. The image changes from positive to negative depending on the viewing angle. This is the main key to identification.
Deterioration. Tarnishing is the most common problem and can cover the entire surface of the plate.
Copper corrosion can occur, where the fractured silver layer exposes the underlying copper layer, leaving behind green and blue copper salts.
Black spots and accretions are sometimes found over the plate. Evenly distributed spots may be the result of residues from the original processing.
Another potential problem is the large needle- shaped silver sulphide crystals which are formed within deeply tarnished films.
Flaking, usually around the edges, is often the result of excessive gold toning.
Ambrotypes: 1851–c1880s
The ambrotype is a variant of the wet collodion process.
Structure. The ambrotype is an under-exposed collodion emulsion on glass. It appears as a negative until a black backing turns the image into a positive.
Ambrotypes usually have their own decorative and protective cases.
Appearance of image. The ambrotype has quite low contrast—the whites appear as dull grey and detail is less visible in the shadow areas. It can be viewed from all angles.
Deterioration. The collodion emulsion may weaken, crack or flake. It may also separate from the glass.
Decomposing collodion releases gases, such as nitric oxide and nitrogen oxide, which combine with atmospheric moisture to form nitric acid— this attacks the cellulose in the collodion.
Atmospheric pollutants and residual processing chemicals can cause the collodion image to deteriorate.
Silver sulphiding will appear as red and green discolouration.
The glass support can break and glass splinters can scratch the emulsion.
If the ambrotype is varnished, UV radiation may cause discolouration and yellowing of the varnish.
The painted black backing often flakes off, leaving what appear to be holes in the image.
Tintype, ferrotype, melainotype: 1854–c1930s
Structure. The tintype was a variation on the ambrotype and was a method for making direct, positive images in the camera on a black or chocolate-brown, enamelled iron plate.
The plates were originally coated by the wet collodion process; but dry plates were later manufactured.
Unmounted tintypes are easily identified by their iron base.
Appearance of image. Tintypes have little contrast. Whites appear as dull grey and shadow areas have little detail.
Deterioration. The collodion emulsion may become weak, crack or flake. It may also separate from the plate.
Decomposing collodion releases gases, such as nitric oxide and nitrogen oxide, which combine with atmospheric moisture forming nitric acid— this attacks the cellulose in the collodion.
Atmospheric pollutants and residual processing chemicals can cause the collodion image to deteriorate.
The iron support may bend or be deformed, cracking the collodion emulsion. This often occurred because many tintypes were sent through the mail.
Thin lines of rust can be seen under raking light on some tintypes.
Opaltypes: c1890s
The opaltype is a photographic image on opaque white glass.
Structure. The photographic image is on an opaque white glass.
The base image is usually black and white, but often heavily overpainted.
Overpaint is smudged when attempts are made to dust or clean the image.
Deterioration. The glass support often breaks, and there can be subsequent loss of image from chipping along the break.
Overpaint is smudged when attempts are made to dust or clean the image.
The overpaint can become quite dirty and/or stained.
IMPORTANT: The overpaint is usually very soluble in water—don’t attempt to clean the surface.
Salted paper prints: developed 1839, widely used 1860–c1890
Structure. One-layer structure—the visible image is formed directly in the paper. The light-sensitive material is embedded in the paper.
Appearance of image. The image is reddish- brown, purple or yellow-brown when processed properly; it can be lilac, pale-blue or a lemon yellow if improperly processed.
The paper fibres are clearly visible under magnification.
Deterioration. The paper used in salted paper prints is susceptible to the same sorts of deterioration as other papers—it becomes brittle, stained and acid burnt.
The prints fade quickly because of improper processing, atmospheric pollution, poor-quality adhesives and mounting materials, resulting in:
variations in colour;
edge fading; and
small yellow dots and lack of highlight detail.
Exposure to UV radiation for prolonged periods causes severe fading.
Platinotypes: 1880–c1930
Structure. Platinotypes have a one-layer structure.
Appearance of image. Platinotypes have a very stable image: there is no fading or silvering out. They are silvery-grey in colour, with a matt surface.
The paper fibres are clearly visible under magnification, and give a rich, velvety texture.
Deterioration. The image, itself, is stable with no fading or silvering out. The processing includes acidic cleaning baths, which contribute to the deterioration of the paper.
Platinum prints are brittle, often with cracked or broken corners.
Residual iron salts plus the acids which are present, contribute to the eventual discolouration of the paper.
Cyanotypes: used c1885–c1910, very rare 1842–1880
Structure. Cyanotypes have a one-layer structure.
Appearance of image. Cyanotypes have a uniform, bright blue image. The surface is matt, with the paper fibres clearly visible under magnification.
Deterioration. The paper used in cyanotypes is susceptible to the same sorts of deterioration as other papers—it becomes brittle, stained and acid burnt.
The blue image fades but can be partially restored by storing it in the dark.
IMPORTANT: Alkaline conditions will fade the blue image; therefore alkaline-buffered enclosures should not be used with cyanotypes.
Albumen printing-out papers—POP: 1850–c1890
Structure. An albumen print is a two-layer system, with an albumen layer holding the sensitised silver on top of a paper support.
Appearance of image. Albumen prints generally produce detailed images.
It is possible to see the paper fibres through the binder layer in highlight areas, when examined under magnification.
Albumen prints can be warm red-brown, a yellow- brown, purplish-brown or purplish-black. Most albumen prints are yellow in the highlight areas.
Deterioration. Typical damage includes fading, yellowing of highlight areas, brittle paper and cracking of the albumen.
Oxidative-reductive deterioration of gold-toned, photolytic silver images results in loss of detail in highlight areas, overall fading of the image and a change in image colour from purplish-brown to warmer, yellower hues.
Sulphiding deterioration, resulting from thiosulphate retained after insufficient washing or from contamination by sulphur in atmospheric pollutants, causes the image to fade to a yellow-brown or to a greenish colour. In some cases, the retention of silver thiosulphate due to the use of exhausted fixer baths, results in the image fading to a greenish- black colour. There is much more staining, usually greenish-yellow, in non-image areas.
Tinting dyes, added to albumen to counteract the warm tones of the image, are extremely unstable and fade readily. High temperatures and relative humidity will also adversely affect these dyes.
Structural problems lead to severe cracking of the albumen layer.
Yellowing of the albumen layer is caused by a protein-sugar reaction. Storage and display conditions are critical in controlling the rate of this reaction, and therefore the extent of yellowing. The key environmental factors are relative humidity, and exposure to UV radiation and to visible light.
Gilt inks were often used in association with albumen prints on cartes-de-visite. These inks, made with bronze powder and zinc, flake quite readily. When the flakes come into contact with the image, they cause local discolouration and spotting of the photographic image.
Albumen prints have a strong tendency to curl when they are not stuck down to a backing.
Collodion printing-out papers—POP: 1880–c1910
Structure. Collodion papers are a three-layer system with the paper support, a baryta layer over the paper—completely hiding the paper fibres— and the collodion emulsion layer on top of the baryta layer.
Appearance of image. The colour of a collodion print varies, depending on the halide salts and toners used during processing.
Glossy collodion prints were usually gold-toned and had a warm tone.
Matt collodion prints were usually gold and platinum-toned and had an olive-black tone. Matt prints were also more stable and resisted fading.
Pigments or dyes were sometimes added to the baryta layer of collodion papers, to make them appear reddish or bluish in colour.
Deterioration. The collodion layer is not flexible. Movement in the paper support due to changes in relative humidity causes hairline cracks to appear in the surface. But, unlike albumen prints, these hairline cracks do not become larger.
Poor storage and handling are serious problems, because the emulsion layer is extremely thin and has very poor resistance to abrasion.
For glossy, gold-toned prints, oxidative-reductive deterioration includes loss of highlight detail, a shift in image colour from purple to warm, reddish-brown and overall fading. Image deterioration is often accompanied by silver mirroring—silvering out—and abrasive damage.
Matt prints are much more stable and show less fading, mirroring and colour change.
Sulphiding deterioration includes fading of the highlights and an intermediate stage of blackening of the image in the middle tones and shadows, followed by fading of the image to a yellowish or greenish-brown.
Matt collodion prints are less affected by sulphiding than glossy collodion prints.
CAUTION:
Never use alcohol on collodion— collodion is soluble in alcohol.
Gelatine developing-out papers—DOP: 1880–present
Structure. Gelatine prints have a three-layer system, with the paper support, a baryta layer over the paper—completely hiding the paper fibres—and the gelatine emulsion layer on top of the baryta layer.
Appearance of image. The paper fibres are not visible through the binder layer.
Gelatine developing-out papers have a near-neutral image colour: a soft slate-grey which sometimes has a greenish-grey caste.
Print surface may be glossy or matt.
Deterioration. The most common types of image deterioration are caused by oxidative-reductive reactions, resulting in:
overall fading;
loss of highlight detail;
yellowing in the lighter areas of the image, fading of lighter tones and overall fading; and
silver mirroring—silvering out—in shadow areas. Nearly all 19th century gelatine developing-out prints are affected.
In advanced cases of oxidative-reductive deterioration, the original black image colour fades to yellow-brown with yellow highlights. These colour changes are caused by physical changes in the filamentary silver on a sub-microscopic level.
Sulphiding: the symptoms of sulphiding resemble those of oxidative-reductive deterioration.
If you have a problem related to the identification, treatment, storage or display of photographs contact a conservator. Conservators can offer advice and practical solutions.
For further reading
Baldwin, Gordon 1991, Looking at Photographs: A Guide to Technical Terms, The J. Paul Getty Museum, Malibu, California.
Buckland, Gail 1980, Fox Talbot and the Invention of Photography, University of Queensland Press, St Lucia.
Cato, Jack 1985, Conservation of Photographs, Eastman Kodak Company, Rochester, New York.
Colligan, Mimi 1991, In Focus—150 Years of Australian Photography, Griffen Press, generated by Australia Post Philatelic Group, Adelaide.
Coote, Jack H. 1993, The Illustrated History of Colour Photography, Fountain Press, Surrey, England.
Crawford, William 1979, The Keepers of Light, Morgan & Morgan, Dobbs Ferry, USA.
Daniels, Patrick 1978, Early Photography, Academy Editions, London.
Davies, Alan & Stanbury, Peter 1985, The Mechanical Eye in Australia—Photography 1841–1900, Oxford University Press, London.
Eastman Kodak Company 1985, Storage & Preservation of Microfilms, Eastman Kodak Company, Rochester, USA.
Eaton, George 1957, Photographic Chemistry, Morgan & Morgan, Dobbs Ferry, New York.
Eder, Joseph Maria 1978, History of Photography, Dover Publications, New York.
Ehrlich, Richard 1984, Dictionary of Photography, Longman Group Ltd, Harlow, Essex.
Focal Press, 1974, Colour Prints: The Photographic Technique of the Colour Positive, Focal Press, London.
Focal Press 1993, Making Kallitypes—A Definitive Guide, Focal Press, Butterworth-Heinemann, Boston.
Focal Press 1983, Storing, Handling and Preserving Polaroid Photographs: A Guide, Focal Press, Publication Department of Polaroid Corporation, Boston.
Freeman, Michael 1985, Instant Film Photography— A Creative Handbook, MacDonald & Co., London.
Frost, Lenore 1992, Dating Family Photographs 1850–1920, Lenore Frost, 8 Cliff Street, Essendon, Victoria.
Gernsheim, Helmut 1982, The Origins of Photography, Thames & Hudson Ltd, London.
Gilbert, George 1980, Photography: The Early
Years —A Historic Guide for Collectors, Harper & Row, New York.
Hawkins, G.L., 1933, Pigment Printing—The Bromoil Process from the Negative to the Transfer, Henry Greenwood & Co. Ltd, London.
Institute of Australian Photographers 1979, The Story of the Camera in Australia, Institute of Australian Photographers, Melbourne.
Jeffrey, Ian 1981, Photography—A Concise History, Thames and Hudson, London.
Keefe, Laurence E. & Inch, Dennis 1990, The Life of a Photograph, Butterworth Publishers, Stoneham, M.A.
Kraszna-Krausz, A., ed. 1965, The Focal Encyclopedia of Photography, Focal Press Ltd, London.
Martin, Elizabeth & Ride, Peter, 1988, Collecting and Preserving Old Photographs, William Collins Sons & Co. Ltd, London.
McDonald, John & Cole, Melba Smith 1981, How to Make Old Time Photos, Tab Books Inc., U.S.A. Miller, Russell 1974, Click, Marshall Cavendish, London.
Permutt, Cyril 1986, Collecting Photographic Antiques, Patrick Stephens Ltd, Wellingborough.
Reilly, James M. 1986, Care and Identification of 19th Century Photographic Prints, Eastman Kodak Company, Rochester, New York.
Rempel, Siegfried 1987, The Care of Photographs, Lyons and Burford Publishers Inc, New York.
Richter, Stefan 1989, The Art of the Daguerreotype, Penguin, London.
Ruby, Jay 1995, Secure the Shadow—Death and Photography in America, the MIT Press, London, Massachusetts, USA.
Stroebel, Leslie D. & Zakia, Richard D., eds. 1993, The Focal Encyclopedia of Photography, 3rd ed., Butterworth-Heineman, Boston.
The Editors of Time-Life Books 1973, Caring for Photographs, the editors of Time-Life Books Inc, U.S.A.
Victoria and Albert Museum 1983, A Guide to Early Photographic Processes, Victoria and Albert Museum, London.
Wall, E.J. 1902, Carbon Printing, Hazel, Watson & Viney Ltd., London.
Wilhelm, Henry 1993, The Permanence and Care of Colour Photographs: Traditional And Digital Colour Prints, Colour Negatives, Slides and Motion Pictures, Preservation Publishing Company, Grinnell, Iowa.
Willis, Anne-Marie. 1988, Picturing Australia—A History of Photography, Angus & Robertson, London.
Self-evaluation quiz
Question 1.
The causes of damage to photographs can be broadly divided into two categories—physical damage and chemical damage. Name three examples of each.
Question 2.
If you must handle photographs, you should:
a) handle them as little as possible;
b) wear cotton gloves or surgical gloves;
c) always have clean hands;
d) place the photographs on rigid supports;
e) all of the above.
Question 3.
When labelling photographs you should:
a) use biro or felt tip pen;
b) label each photograph on the edge of the back of the print, using a soft pencil and minimum pressure;
c) attach a paper label to the photograph using a paper clip;
d) press hard to make sure the label can be seen.
Question 4.
If you have a damaged photograph you should:
a) place it in a protective sleeve or wrapper;
b) mend it with sticky tape;
c) seek the advice of a conservator;
d) use rubber cement to stick it to an album page.
What are the ideal temperature ranges and relative humidity for storage of photographs?
a) 25°C±2°C and 60%RH
b) 18°C±2°C and 30–50%RH c) 15°C±4°C and 10–20%RH d) 20°C±2°C and 50%RH
Question 6.
If you have a photographic collection which has been kept in an extreme environment and is in good condition, you should:
a) take every possible step to change the storage environment so that it meets the recommended ideal conditions;
b) take steps to improve storage methods and materials but do not alter the environment to meet the recommended ideal conditions;
c) install air conditioning.
Question 7.
Of the following materials, which are good for storing photographs and which are bad for photographs?
butchers’ paper, metal furniture with baker enamel finish, PVC, coated paper, polyester, photographic storage paper, museum mount board, furniture made from uncured wood, black papers containing sulphur, coloured papers, polypropylene, newsprint, photographic-quality wood pulp papers?
Question 8.
Providing layers of storage with individually wrapped photographs placed inside boxes, and in some cases these boxes placed in other boxes:
a) gives maximum protection from fluctuations and extremes of relative humidity;
b) is wasteful of materials;
c) is a good way to fill in time but doesn’t do much for the collection;
d) protects photographs from dust, pollutants, insects and the damaging effects of light.
Question 9.
What function does an acid-free window mount/mat have in a conservation framing system for photographs?
a) The mount/mat provides a space between the glazing and the image.
b) The border around the photograph can enhance the appearance of the photograph.
c) The mount helps to buffer the photograph from changes in relative humidity.
d) All of the above.
Question 10.
The best kind of light for the display of photographs is:
a) tungsten incandescent bulbs;
b) daylight;
c) low wattage fluorescent tubes;
d) spotlights for individual images.
Answers to self-evaluation quiz
Question 1.
Answer: Answers could include:
Physical
dog-eared corners
insect attack
abrasion and scratching
tears and cuts
creases
peeling emulsion
indentations from labelling
Chemical
- fading of the image
- yellowing of B&W; images
- colour change of colour prints • staining
- fading of colour prints
- stains from repair tapes
- silver mirroring (silvering out)
Question 2.
Answer: e): all of the above. Photographs are very susceptible to damage; but if you must handle them they should be supported and you should not handle them directly—wear gloves. Hands should be clean to minimise the risk of oils and dirt being transferred to the photographs.
Question 3.
Answer: b). This is the best way to label photographs. a), c) and d) are wrong. Inks can spread and cause staining; pressure can crack the emulsion and paper clips can damage photographs.
Question 4.
Answer: a) and c). Some aspects of conservation of photographs are complex and you should protect your damaged photograph and seek the advice of a conservator. Never use sticky tapes and rubber cement on photographs.
Question 5.
Answer: b). These are the ideal conditions but they cannot always be achieved.
Question 6.
Answer: b). a) and c) are wrong. If the collection is stable, don’t try to alter the storage environment so that it meets the recommended ideal conditions. This could cause more harm than good. The emphasis should be on long-term stability.
Question 7.
Answer:
GOOD
photographic-quality rag and wood pulp papers
plastics such as archival-quality polyester and polypropylene
photographic storage paper
photographic, conservation or museum quality mount board
metal furniture with baked enamel finish
BAD
poor-quality papers such as newsprint or butchers paper
black papers and boards — these often contain sulphur
coloured papers and coated papers
polyvinyl chloride — PVC — a common plastic
- furniture made from uncured wood or recently painted furniture
Question 8.
Answer: a) and d). Providing layers of storage is very protective and wastes neither time nor materials.
Question 9.
Answer: d).
Question 10.
Answer: a). Tungsten incandescent bulbs give out very little UV radiation and are not as hot or as intense as spotlights.