Reilly, James M. The Albumen & Salted Paper Book: The history and practice of photographic printing, 1840-1895. Light Impressions Corporation. Rochester, 1980.
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"If we find that a little sour paste is quite sufficient to injure the picture, it is no satisfaction to us to be told that it consists of metallic silver, one of the most indestructible of metals."
--T.F. Hardwich
May, 18561
Once the prints have been washed and dried, they require further handling before they can be displayed or stored in the safest and most advantageous way. The choice of finishing materials and treatments bears directly on both the attractiveness and permanence of albumen and salted papers. Proper storage is also essential to optimum permanence in any photographic material. This chapter presents a recommended contemporary approach to the finishing and storage of albumen and salted papers, together with some historical notes on 19th-century practice.
Fig. 41. Carte de visite albums, ca. 1870. At right is a stereo viewer.
The characteristics of the prints themselves will determine the most suitable method to prepare them for storage or display. Depending on the thickness of the rawstock and the type of organic binder on the print surface, most prints will need some type of flattening treatment after drying. The most common method is to place them between acid-free blotters under weights, or in a book press. This process should be undertaken when the prints are slightly damp or at least not when they are bone-dry, and above all it requires patience. Do not try to hasten the process with excessive pressure, although a fair amount of pressure is needed to accomplish the flattening.
The use of heat in the process of drying or flattening may alter the appearance of some types of salted papers, especially plain salted papers. Upon heating the prints turn colder in image color and become somewhat darker. This technique was actually a part of the process that Fox Talbot used in the production of his prints. The last step in finishing his prints was to go over them with a hot iron to "intensify" them. Drying salted paper prints in a heated drum type of dryer may similarly change them.
Ideally, once the prints are flattened they can be placed in a sleeve or mat without a mounting process of any kind. Most salted papers, because they are made on relatively heavy paper and do not have a great deal of binder material on their surface, can be simply matted and do not require mounting. Mounting is a process that should be employed only when necessary, and not as a matter of course. Unfortunately, the thinner papers used in albumen printing and the tendency to curl imparted by heavy layers of albumen will often necessitate that prints be flattened by mounting them onto a suitable material.
Fig. 42. Trimming prints using a rotary blade trimming knife and brass templates. A rotary knife made it easier to follow the outlines of curved templates.
A look at the 19th-century approach to the finishing of albumen prints is instructive, because it relates quite closely to modern practice. It is rare to encounter 19th century albumen prints that have not been mounted onto some kind of cardboard mount. The main reason for this is the fact that the thin paper stock used for albumen printing cannot resist the tendency to curl of the layer of albumen itself. The force exerted by a thick layer of albumen is quite enough, if a print has been incorrectly mounted, to tear the print in half; the impossibility of getting such a print to lie flat of its own accord is obvious. Even if a window mat is used to keep an unmounted albumen print relatively flat, most prints have undesirable ridges, creases and "bumps" in the print surface that catch the light and detract from the image.
The process of mounting an albumen print helps to impart more depth and contrast to the image, and creates a smooth, level surface which can be viewed from different angles without the interference of these uneven surface reflections. In the 19th century the prints were mounted when damp, and if they had become dry, they were rewetted and blotted before mounting was attempted.2 The modern mounting method given below also adopts this precaution.
Fig. 43. Advertisement for Higgins' Photo Mounting Paste, 1894, described by the manufacturer as "not a starch or flour paste, but a vegetable glue."
The adhesive used for mounting albumen prints was usually starch, although gelatin3, gum arabic4, dextrine5 and albumen itself6 were also used. Sometimes starch and gelatin were mixed together.7 Photographic conservators faced with the problem of removing albumen prints from their mounts agree that pure fresh starch has proven itself as the best choice for a mountant; it is removable with the least difficulty and has not attacked the prints. Ordinary "glue"--which is an impure form of gelatin--was known to be a cause of trouble even in the 1850's, but it was used as an expedient, along with many other destructive substances such as rancid flour paste and India rubber solution.
The mounting boards used in the 19th century were a constant source of potential danger for the photographic image. A typical 19th-century mount was composed of a thin top and bottom sheet of relatively good quality paper, with a center filler of poor quality pulp board. This pulp center was often loaded with lignin, the noncellulose component of wood, whose presence leads to the acidification of the entire mount and eventually of the photographic print itself. The most common problems seen today that result from poor quality mount boards are brittleness and yellowing in the print caused by acidification of the mounting cardboard, and the brownish-red flecks and stains known as "foxing." This "foxing" may be the result of mold and fungus growth, or may also be caused by the presence of metallic salts in the mount board.8
Staining from decomposed mounting adhesives is also common, either initiated or compounded by the acidification of the mount board. Today, many albumen prints are in desperate need of separation from their original mount and re-mounting on a more durable and less dangerous material. Danger from the mount board is especially acute for albumen prints because they were made on such thin rawstock--very little barrier exists between the silver image and the potentially destructive substances in the mount. Attempting to forestall further damage to albumen prints from defective mounts and mountants is one of the single largest tasks in photographic conservation, and is among the most commonly requested procedures in the conservation of photographic prints.
Fig. 44. "Marion's Self-adjusting Rolling Press & Burnisher," 1884. Note the gas tube in the upper roller.
Fortunately albumen is a very durable substance, and can usually withstand the rigors of unmounting and remounting. More trained and experienced photographic conservators are needed for this task if our photographic heritage--historical as well as aesthetic--is tobe preserved.
In addition to curling the paper, sometimes heavy layers of albumen can have a horny, rough surface that may obscure the finest details. Rolling and smoothing the prints in a press or roller device tends to restore some of the detail and also provides a glossier surface and increased contrast. For this reason, and also to improve adhesion of the print to the mount, albumen prints were routinely subjected to a process of rolling and smoothing after mounting.
There were several styles of rolling machines used in the 19th century, but all of them accomplished the same purpose of making the prints glossier and smoother. Small prints--especially "cabinet" size portraits and stereo views--were often given an extra glossy finish in a heated roller device called a "burnisher." In skilled hands a burnisher could produce a mirror-like gloss on albumen prints. The operators of portrait studios in the 1880's and 90's sometimes ballyhooed the gloss of their prints by giving them fantastic names like "French Enamel" and "Extra Superior Finish."
Fig. 45. A flat-bed type of rolling press, of English manufacture.
Some types of rolling machines were similar to wringers on old-style washing machines. One roller was smooth and did the work of polishing the print while the other roller sometimes had ribbing to bite into the mount and propel the print through the machine. Many small photographic prints of the period 1875-1890--landscapes, portraits and stereo views--have cross-hatched indentations on the back of the mount. Such prints were rolled in a wringer-type rolling machine with a ribbed drive roller. In other cases the back side of the print mounts will simply be noticeably shiny with a "squeezed" appearance; this is evidence of having been rolled in a flat-bed or smooth-roller type machine. Flat-bed style machines resembled a copperplate etching press and could be used with either mounted or unmounted prints. The prints were placed face down on the steel bed of the press and a large roller applied pressure to the back.
The object of finishing (and mounting, if necessary) is to present and store prints in the safest and most attractive way. A simple, direct approach is to place prints in individual transparent polyester sleeves, together with a piece of two-ply, acid-free rag board to impart rigidity and prevent creasing of the print during handling. These are available in most of the common photographic sizes, and are a satisfactory way to store and examine prints with a minimum of wear and tear. Any cataloging or identifying information that is to be placed directly on the print should be lightly written on the back of the print in pencil, and as close to the edge as possible. These polyester (also called MylarTM) sleeves will not damage the prints at normal humidities and temperatures, and at the present time do appear safe for long-term storage.
For prints that merit more attractive presentation or more protection in storage, a window mat is the preferred method. A window mat is two superimposed pieces of very high quality cardboard that are hinged together along one edge. The print lies between the two pieces of board and is visible through a hole--called the "window"--cut in the top piece of the board. Window mats should be made from what is commonly called "museum board," which means that it is composed of 100% cellulose fiber and is acid-free. Although several other kinds and grades of mat boards are available, it is best to select only those materials that will lead to optimum permanence. In choosing mat board for use with albumen and salted paper prints, most museums choose a cream or ivory-tinted board, in order to harmonize with the warm colors of print-out silver images. The hinges of the mats should be made of linen treated on one side with a special acid-free, water-soluble adhesive.
The "mat," as it is usually called, fits into a frame as a unit when a print is to be framed. The "window" of the mat is cut with a special beveled cutter so that it does not cast a shadow onto the edge of the print. If a print is to be stored in a window mat, a piece of acid-free paper or polyester sheeting is placed on top of the print (under the window) in order to protect the print from dust and mechanical damage. These two methods--transparent sleeves and window mats--are the most common approaches to presentation and storage used in photographic collections at the present time.
One advantage of both the sleeve and the window mat are that they form a safe environment for the print yet are not permanently attached to it. In the case of the window mat, there are two approaches to holding the print in position under the "window" of the mat. The first is to use what are called mounting corners, which are hollow folded paper triangles made from acid-free paper. The corners are held in place by the same kind of linen tape that forms the hinge of the mat. To use mounting corners, the four corners of the print are inserted into the folded triangles, the print is positioned under the "window," and finally the paper triangles are adhered to the bottom piece of the mat.
If the print has no borders and is all image area, another approach is necessary. This alternative method involves the use of "hinges," which are slips of very thin Japanese paper that are adhered along one edge of the print and then adhered to the bottom board of the window mat after the print has been correctly positioned. The adhesive for this purpose should always be a specially prepared paste of wheat or rice starch. The method of preparing this paste will be detailed later on in this chapter. The actual Japanese paper hinges should be about 2 inches long and 1 inch wide; two of them are usually needed. The hinges should be cut from the sheets of Japanese paper by tearing along a straight edge, and not by cutting with a scissors, because in this way the fibers taper smoothly off and there is less chance of the hinges showing through a print on thin paper. Just a small portion of the narrow dimension of the hinge need protrude onto the back of the print itself. The goal in the use of hinges (as in all conservation treatments) is to make them as reversible--that is, removable without trace or damage to the print--as possible and still have them perform the task of holding the print in position. Longer hinges than necessary are sometimes used so that if the print requires re-matting, the hinge may be simply cut off with enough of the hinge remaining to reattach the print in another mat.
The following is a very satisfactory method of mounting albumen and other sorts of photographic prints. It is useful for both modern albumen prints and 19th-century prints that have been removed from their original mounts and are in need of remounting. This method was worked out by David E. Kolody, a photographic conservator in Boston, Massachusetts, and it appears here through his courtesy.
Although more complicated than other mounting methods, this method has several advantages: first, it adheres the print to the support in such a way that an absolutely flat and smooth surface is created. This is important because it most closely approximates the surface quality of the print on its original mount. Albumen prints are generally most effective when their surface is absolutely flat and smooth. Remarkably, albumen prints mounted by Kolody's method retain a "rolled" appearance on their new support, even though no high-pressure rolling press is employed in the mounting procedure. Second, this method is equally effective with large or small prints. It allows 18 x 24 inch prints to be mounted almost as easily as 8 x 10's. These large prints, by no means uncommon, are notoriously difficult to work with. Third, the method is easily reversible without resorting to strong solvents, and does not permanently attach the print to its mount. Fourth, no heat is required and there is no danger of altering the color of a print or otherwise damaging it with heat. Dry mounting (in the modern sense) should never be used with albumen or salted paper prints, because of color shifts caused by heat, and the irreversibility of the process.
The basic principle of this mounting method is to provide a rigid temporary support of PlexiglasTM on which the print is mounted and dried, so that the print is held flat until it has become completely dry and its internal forces have equalized out. Of course, if the print and its mount were simply pasted down on the PlexiglasTM they would dry flat, but there would then be no way to remove the print and mount from the PlexiglasTM.. The solution to this is to adhere a sheet of polyester cloth to the PlexiglasTM, then the mount to the polyester cloth and finally the print to the mount. All these steps are done in immediate succession, and the last step is to protect the face of the print with waxed paper and roll the print flat with a roller. The whole "sandwich" is allowed to dry, the polyester cloth is then stripped from the PlexiglasTM, and finally the polyester cloth is peeled away from the back of the mounted prints.
The adhesive used in this method is a paste made from boiled refined wheat starch. Wheat starch paste provides good adhesive properties, is easy to work with and is inexpensive. It is necessary to prepare the starch paste at least one day before it will be used. One brand of wheat starch that has been successfully used is Aytex a powdered edible wheat starch manufactured by General Mills Chemicals, Inc. To prepare the paste, place 200 ml of wheat starch (volume measurement is convenient and sufficiently accurate) in a 4-quart enamel or glass saucepan. It is important that no iron or steel make contact with the starch solution at any stage in its preparation or use. Slowly and with constant stirring pour in 1400 ml of distilled or deionized water. Stir until there are no lumps and allow this mixture to sit overnight. An old wooden spoon that has been deacidified with magnesium bicarbonate is the best implement with which to stir starch pastes, both when cold and during cooking.
The following day, place the pan over a medium-low flame and stir until the mixture starts to thicken. The starch must be stirred constantly during its entire cooking phase or it will burn. After the mixture starts to thicken, cook with constant stirring over a low flame for 20 additional minutes. The properties of the gel that will form as well as the adhesive properties of starch pastes are determined by the length and the method of cooking, so it is important to follow the directions closely. After the mixture has cooked, add 0.4 ml of a saturated solution of thymol in methyl alcohol. Thymol is a fungicide and does not appear to affect the adhesive properties of the paste. Place the paste in a covered container and refrigerate. The paste may be used when cool and gelled, or may be refrigerated for up to one week before use.
To use the paste, the refrigerated gel must be diluted in a blender. Place the cold gel together with 2/3 of its volume of cold distilled water and blend for a few seconds at low speed, and then for 30-40 additional seconds at high speed. The paste thus formed is ready to use, and it should be kept covered to prevent a "skin" from forming and to keep out dust. It is most unpleasant to mount a print and discover particles of dirt or hardened starch trapped under the print. The prepared paste should be used on the same day.
The rigid support required for the purpose is a piece of 5/16 or ½ inch PlexiglasTM somewhat larger than the total area of prints to be mounted. The PlexiglasTM is first prepared by sanding one surface with a waterproof sandpaper (200 grit) used wet, until it has assumed a matte surface. This roughened surface is necessary to allow the polyester cloth support to grip the plastic. To mount a print, first clean off the PlexiglasTM sheet with water and thoroughly dry it. Then apply an even coating of starch paste to the matte surface of the PlexiglasTM. Do not use a brush that has an iron or steel band to hold the bristles; a flat Japanese brush or a foam brush should be used to apply the paste.
The temporary cloth support used in this procedure is a single thickness of white polyester crepe, available in most fabric stores. This material is tightly woven and has a slight surface texture. It is used in sewing as a liner for garments. It must be larger than the piece of PlexiglasTM and it is helpful to make a seam around its perimeter to keep the cloth from unravelling. The polyester cloth must be laundered before each use.
Lay the cloth on the prepared PlexiglasTM by holding it by two opposite corners and bowing it in the center; let the middle touch down first and lower the corners until it lies flat on the PlexiglasTM. Stretch it first in one direction and then the other. After working out the air bubbles as much as possible, apply an even layer of starch paste on top of the polyester. Take care that the cloth is now smooth, flat and free of bubbles.
The mount for albumen prints should be a sheet of heavy, smooth, all-rag paper of very high quality. The mount must first be pre-swelled by dampening it with a spray of distilled water, first on the front (watermark right-reading) side and then on the back side. The paper should get fairly wet and then be blotted between acid-free blotters. Pre-swelling helps to distribute the internal forces more evenly during drying. Note the grain direction of the mounting paper; the idea is to have the grain directions of the print and the mount crosswise to each other so that the tendency to curl is minimized and the print lies flatter. The grain direction of the unmounted print is always the direction of the print's natural curl.
To lay the pre-swelled mounting sheet on the polyester, grasp it by two opposite corners and place the center of the sheet down first. Lay the corners down with a rolling motion to try to force out any air bubbles. Smooth out the paper and apply another coating of starch paste on top of it. Experience will show what amount of paste is enough, but do not skimp or the print will not adhere satisfactorily. The use of too much paste will be apparent when the print is smoothed out.
Prints should be wetted with a spray of distilled water before mounting them. Spray both sides and blot them between sheets of acid-free blotting paper so that they are only damp when actually placed down on the mount. Remember to place the grain direction of the print perpendicular to that of the mount. The starch paste may need to be renewed by a fresh brushing over just before mounting. Leave room on the mounting paper between prints for hinges to be cut out later. As many prints as practical may be mounted on each large sheet of mounting paper.
Place waxed paper over the face of the prints and smooth them out with a hard rubber roller. Hold the waxed paper in place and start smoothing from the center of each print toward the edges. Large prints may require several sheets of waxed paper; overlap the sheets of waxed paper to prevent starch from reaching the face of the prints. Avoid excessive pressure in rolling or the paste will be forced out and the prints will not adhere to the mount. Peel off the waxed paper and remove any paste from the face of the prints using a ball of damp cotton.
Allow the whole "unit" to dry for at least 12 hours, depending on humidity, or until there is no "damp" smell from the starch. It is much better to be over-cautious in estimating when the prints are dry than too hasty. The pieces of PlexiglasTM may be placed upright to dry.
When completely dry, the first step in removing the prints is to pull away the polyester cloth from all four sides of the PlexiglasTM, up to the point where the mounting sheet begins. The grasp the polyester with two hands and pull it away at a low angle from the PlexiglasTM in one smooth motion. It is better to grasp the polyester across the short dimension of the mounting sheet and pull it the "long way," because this avoids unnecessary stress for the mounted prints.
When the polyester has been pulled off the PlexiglasTM, turn the cloth over and gently peel the cloth away from the back of the mounting paper. Hold on to the paper to support it while peeling away the polyester. When the mounting sheet has been removed from the cloth, trim the mount to within 1/8 inch of the prints, allowing at the same time for two hinges 1 inch wide and 2 inches long on each print. The prints are now smooth, flat and ready for matting.
Kolody's mounting method exerts considerable stress on the albumen layer of the print as it dries. While such stress does not usually harm prints, especially newly made prints, some 19th century prints may have a visibly weakened or severely cracked albumen layer. In this event mounting by Kolody's method is not recommended, because the stress of mounting may worsen the cracking of the albumen layer.
Prints are best stored in boxes and containers made especially for the purpose and sold by various suppliers to museums and libraries. Metal boxes are a good choice because they eliminate the danger of contamination from poor quality cardboard and wood itself. Metal boxes made for print storage are likely to be costly because special precautions are necessary in selecting and applying the finish on all metal surfaces. Storage boxes made from acid-free board are considerably less expensive, but may not have the durability required for use in a working collection. Vinyl covered print "cases" with metal clasps and hinges are more suitable to hard use, but may have to be re-lined with acid-free paper to insure a safe environment for prints. All prints should be sleeved or matted to protect them in storage.
Always be sure that no gases are emitted from paints or varnishes used on storage containers. Do not store prints in wooden cabinets on a long-term basis unless the cabinets are specially treated or metal-lined. Wooden cabinets may be thought of as large envelopes of the coarsest kind of paper. Gases that attack the paper support and the images of prints may also be present in the general environment of the room where prints are stored, and this must be taken into consideration in selecting the location of a print collection within a building. High levels of automobile exhausts or ozone emitted from an electrostatic copier are both very destructive.
Anything that accompanies the prints in storage, especially inside the sleeves, should be of the highest quality. Do not store prints in the company of acidic or poor-quality papers or board, or together with adhesives, nitrate-base negatives or anything else likely to pollute the storage environment.
The single most important consideration in print storage is that temperature and humidity should not undergo sudden drastic changes, and excessive heat and humidity should definitely be avoided. A satisfactory temperature and humidity range is 18-20°C at 35-45% R. H. The reason why control of temperature and humidity is so important is the fact that these factors govern the rate of all possible destructive reactions that prints might undergo. The higher the temperature and humidity, the faster all the various mechanisms of deterioration will operate. Active control of temperature and humidity conditions is expensive, but is it the best and most necessary investment that any photographic collection can make.
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