PMG Cased Photographs

Category:Photographic Materials
Category:Photographic Processes
Category:Materials and Treatment
Category:Housing
Category:Bibliography
Cased Photographs. Including daguerreotypes, ambrotypes and tintypes was published as Chapter 2 of the The Photographic Materials Conservation Catalog in 1998, with John McElhone as Page Compiler (see PDF for all contributors listed on page 61). This printed information has served as basis for this wiki page, and current information has being added as necessary. In 2021 Elena Bulat became Page Compiler, expanding and updating text, bibliography and images to keep page current.
Page Information	Page Information
Date initiated 	Month Year (The history log records each time a person contributes, don't add additional dates here).
Page Compiler 	Elena Bulat (since 2021)
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== What are cased photographs? ==
=== Daguerreotype Plates===
Daguerreotypes are direct positive photographs on metal supports. The supports are copper plates clad with a polished layer of metallic silver. The image particles, which lie on the surface of the polished silver, constitute the image highlights; they are primarily composed of silver but may contain small amounts of gold and mercury. 
=== Ambrotype Plates===
An ambrotype is an under-exposed wet collodion negative on glass that appears positive due to the presence of a dark backing or use of dark glass support. In most instances, the image is varnished and placed in a case for safe-keeping. 19th century ambrotypes were displayed in miniature cases just like daguerreotypes.
The “common ambrotype” is a clear glass support backed with a dark piece of textile, metal, secondary glass or paper, or painted directly onto the back of the image. The “ruby ambrotype” is printed onto a dark glass support that is red when viewed in transmitted light. This technique doesn’t require additional backings. Known examples of ambrotypes printed on yellow or blue glass supports exist, but the occurrence is rare.
=== Tintype Plates===
Tintypes are direct positive photographs produced on a lacquered iron Usually both sides of the metal plate were coated with the black (or brown) pigmented lacquer (sometimes called "japanning" or "Japan varnish"). One side of the plate is subsequently coated with iodized collodion. The wet collodion layer is then sensitized, exposed and developed. 
==Cases and Other Housing Formats==
===Types===
Hinged Case (commonly found on American and British plates) 
The case is a multiple component structure which works to protect the photographic plate from physical damage and from the environment. Original cases also provide an appropriate aesthetic setting for the image. 
The plate is contained in a package consisting of several layers. The plate, together with a metal mat and a cover glass, may be bound together with an adhered paper strip. 
The metal mat is sheet brass. It is stamped (or molded) with a decorative pattern and may be etched to give an overall surface texture. Mats may be gilded and are usually coated with a colored varnish (shellac tinted with a variety of natural colorants). A mat provides a decorative setting for the image and keeps the cover glass, if present, away from the image surface. 
Note that while it may be possible to date brass mats of the 1840-1865 period on the basis of their thickness and decorative finish, this does not necessarily relate to the image date since mats may have been interchanged. 
The preserver is a flexible strip of a copper alloy foil that folds around the glass/mat/plate package. The use of preservers on daguerreotypes began later in the 1840s, possibly 1847. They are usually stamped with a decorative pattern and serve a decorative purpose as well as protecting the paper binding, if this is present. Most importantly, the preserver preserves the daguerreotype image from tarnishing by preventing air ingress; it does this by pressing the package components together, most effectively when the package is pressed into the case. (See notes on the retainer also.) 
Occasionally, no preserver was used; in such instances, the sealing tape is adhered to the edge of the cover glass but does not extend onto the front surface. This is more often seen in British cases than in American ones, although early American cases often lack the preserver. 
The case is composed of two halves, a cover and a tray, that are hinged together. It may be covered with embossed or plain leather, molded paper or papier-mâché, textile (including velvet), lacquer/mother-of-pearl, or even more exotic materials. Leather-covered cases frequently show gilt tooling. 
The covering materials are adhered to the wooden base. Hinges may be of brass, attached to the trays with small brass nails. The hinge can also be created by extensions of the leather, textile or paper that covers the tray. 
When the hinge is contiguous with the covering material, there may also be an interior hinge to reinforce the exterior one. 
The tray has a velvet-covered cardboard retainer around its perimeter. The retainer presses the components of the package together inside the cavity of the tray and acts to seal the package interior from air infiltration. The case cover holds a cushion -- a convex cotton pad covered with velvet or satin. The cushion reduces the volume of potentially harmful air inside the closed case and provides some protection to the cover glass from breakage. 
The case often has one or two brass hook-and-eyelet clasps attached on the exterior right edge to secure it closed. 
The "Union case" is an American variation made with an early thermoplastic material composed of shellac, cellulosic fibres and pigments; this material was molded to make cases with detailed decorative motifs and representational scenes. Introduced in 1853, they usually have brass hinges and often have an integrated spring clasp rather than hook-and eyelet clasps. 
Occasionally, two or more photographs are contained in the same case. 
Not shown in the illustration (see next page), but frequently encountered in both daguerreotype and ambrotype packages, is the paper sealing tape adhered to the perimeter of these package elements which binds them together. 
Ambrotype cases may differ somewhat from daguerreotype cases. If the ambrotype has not been painted with a pigmented lacquer on the plate verso, a dark-colored paper, textile or glass layer will be included behind the image plate. The cover glass may not be present in ambrotypes where the collodion image layer faces the interior (this having been done to correct lateral reversal of the image). In such instances, the metal mat and the preserver are adjacent to each another. 
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Illustration: T. Pritchard
Passe-partout (European daguerreotypes, stereographs)
Daguerreotypes originating elsewhere than Britain and North America, as well as stereo-daguerreotypes, may be found packaged in this format. It consists of glass and paper elements with a cardboard backing. (See illustration below.) 
Passe-partout with paper mat: The mat is usually a heavy wove paper with drawn or printed decoration. The mat aperture is most often square or octagonal in shape. The cover glass is fixed over the paper mat with a colored paper binding tape adhered around the package perimeter. (Some early American daguerreotypes, especially mourning portraits, incorporate gold-painted paper mats.) 
 
Illustration: T. Pritchard
Passe-partout with reverse-painted cover glass: The earliest examples of this format are quite simple. Later examples include simple decorative lines, elaborate transfer designs or elaborate geometric patterns and decorative painting techniques (for example, tortoise shell patterns). When examined on the verso surface, these reverse-painted glass plates often have a matte-texture paint layer applied over the decorative paint, possibly as a protective layer. 
Both types of passe-partout housings were eventually made commercially and could be purchased by the daguerreotypist. An open flap on the cardboard backing allowed the processed image plate to be placed in position under the aperture and fixed with several strips of adhered paper. The flap was then closed with more paper strips or with a paper sheet adhered over the whole package verso. 
Paper binding tape was adhered to the package periphery. It may be colored or decorated to aesthetically integrate with the rest of the package design. (For instance, coated paper or marbled paper may be used as binding tape.) 
The cardboard backing of the package is usually covered with a colored paper sheet, and inscriptions and labels are often found here. 
Frames 
American, British and European daguerreotypes, ambrotypes and tintypes may be found in wooden, thermoplastic composite or papier-mâché frames. The plates will be contained in the same kind of plate packages that would otherwise be presented in a case or passe-partout. The frame may either be original or a later addition. 
Paper Housings 
Small tintypes are sometimes mounted inside paper mats whose dimensions approximate the carte-de-visite format. These mats consist of a backing sheet onto which the plate is directly adhered, covered by an aperture overmat. The overmats were often decorated with embossed or printed motifs and with the photographer's identification. The top sheet is often adhered to the bottom sheet and to the concealed perimeter of the plate surface. 
=== Condition of Cases===
The leather, cloth or paper case hinges are often the weakest component in a hinged case. It is not unusual to encounter cases with the hinges either partially torn or with the trays completely detached from one another. 
Sometimes the cover will be missing. Hinges will often have been reinforced or replaced, often with poor-quality or inappropriate materials. 
Leather and Paper Case Coverings 
Case coverings are frequently torn or have lost small sections; separation from the wooden base may have occurred. The exterior surface, particularly the raised portions of any pressed pattern, may be abraded, resulting in the loss of color and finish. Leather, particularly leather hinges, may be brittle. Gilt tooled or bronze painted decoration on the case exterior and interior may be soiled or abraded. A variety of surface coatings, especially waxes and oils, may have accumulated during a long history of cosmetic treatments. 
Paper Tape and Mats 
While goldbeater's skin was occasionally used to seal the edge of plate packages, sealing tape was most often made from strips of paper that had a thin layer of water-soluble adhesive applied to one side. Early daguerreotypists used strips of writing paper, but as the craft became an industry, rolls of paper tape prepared specifically for this purpose became available for purchase. The preservation state of the sealing tape depends on the quality of the paper used, the type of adhesive and the amount of mechanical wear that the seal has received in handling. Tapes might have been split open to examine the package interior and then inexpertly resealed. 
Plates inside passe-partout packages were fixed with strips of gummed paper tape adhered to the verso surface of the paper mat or reverse-painted cover glass; these attachments are often found to have desiccated and released. 
Plates in this housing format frequently slip inside the package. 
The paper mats of the passe-partout packages may be light damaged or may show adhesive stains. These packages may have been opened once or several times over the years to examine the plate; they will show evidence of more or less expert resealing. Several layers of backing paper, some of them fragmentary, may have accumulated on the package. 
The paper mats applied to small tintypes may show staining and mechanical damage. Adhesives holding the plate to the paper may have desiccated and failed, leaving the tintype plate loose between the paper layers. The adhesives used may have initiated rusting of the iron support.
 
Glass 
Glass used for both glazing and support materials for cased photographic images was usually commercially available pane glass. There were some companies that sold "photographic" glass destined for use as supports for photographic plates. This glass was free of physical flaws and was relatively colorless, but did not have superior durability or corrosion resistance. 
All glass is subject to physical breakage. Broken cover glass on cased photographs may cause immediate physical damage to the image underneath. In addition, it may lead to chemical deterioration of the image in the localized area under the breakage by allowing the direct ingress of air; this is particularly common with daguerreotypes with cracked cover glasses. 
Some glass formulations are chemically unstable due to a high flux content, especially those with a high ratio of sodium flux in proportion to the alkaline earth flux (calcium and magnesium oxide). Note that glass with a high sodium content produces a yellow-orange fluorescence under UV illumination, whereas glass with a higher alkaline earth content tends to produce orange-magenta fluorescence. Glass corrosion is caused by inherent instability linked to unfavorable environmental conditions. 
Glass corrosion, leading to the accumulation of alkaline materials and silicates on the surface of the glass, is a major cause of deterioration in cased photographs. Unfortunately, the design of the cased photograph package encourages the type of corrosion in cover glass called "static weathering." 
In this process, the inner surface of the cover glass is exposed to a small enclosed air volume; this air is subject to transient periods of high or cycling relative humidity. 
The glass used in photographic packages should be checked regularly for signs of weathering corrosion. It may be easier to detect corrosion films by examining the glass by specular reflection. Look for: 
* early signs -- a faint surface haze or clouding;
* more advanced states of "weeping" glass, including the presence of tiny droplets that lend a "greasy" or "soapy" feel to the surface; these are primarily amorphous sodium silicates (water glass) and have a high pH -- in the range of 10-14 (the presence of alkaline corrosion products may be detected by burnishing a pH indicator strip on to the affected surface);
*needle-like crystals and incrustations on the inner surface of the glass - they may also have spalled off, leaving the crystals on the surface of the photograph below;
*blister-like crystals that appear to have a small darker-colored core;
*mold-like masses on the surface of the daguerreotype plate below, sometimes obviously associated with a spalled-off crystal corrosion product from the cover glass above; these have a "bead-and-thread" morphology reminiscent of Candida spp. but are entirely inorganic. 
Refer to Barger; Smith; White (1989) for more information on cover glass deterioration. See Katherine Whitman's section Glass in Photographic Materials for more details regarding glass history, manufacture, and repair. 
Wood Trays 
The wooden structure of the case may be found in poor condition, with the front or back surfaces warped, joints broken, structural members split, and glue desiccated and released. Side members are often missing altogether. The paper or leather coverings may have begun to lift from the underlying wood structure. 
Composite Thermoplastic 
Union cases may show warpage, "blanched" or roughened surfaces, cracks or other physical damage (often located at the insertion and attachment points of the brass hinges). Storage for extended periods at higher temperatures or excessive light exposure both seem to be damaging. Prior cleaning and cosmetic treatments may include the application of water, detergents, solvents, petroleum jelly, furniture polish and shoe polish. 
Brass Preservers, Mats, Hinges and Clasps 
The most common deterioration observed on the varnished brass mats are the small randomly distributed spots of brown, black or green copper corrosion products that appear to be under the varnish layer but which may effloresce. 
less common is the observation of large fields of even discoloration over sections of a mat. The occurrence of local copper corrosion has been linked to contact with the alkaline products of glass corrosion. Tiny holes in the varnish film and exposure to elevated humidity have also been cited as causes for brass corrosion on mats and preservers. 
Preservers, made from a flexible copper alloy foil, are subject to mechanical stresses and fatigue due to the action of folding and unfolding. 
The most common deterioration of these components is mechanical breakage, usually occurring at one or two of the corners. 
Hook-and-eyelet clasps are sometimes found to have been broken; hooks are sometimes missing altogether. 
Textile Covers for Cushions and Retainers 
The most common deterioration seen on velvet coverings is the accumulation of lint, dust and dried accretions. Cushions may be damaged by insects. 
Retainer coverings may be worn, abraded and compressed; they may no longer provide adequate pressure along the package edge. Silk cushion coverings are sometimes found in a fragile and worn state. While the dyes used on these textiles may be quite sensitive to light, light-induced fading is less frequently encountered because these components have been protected inside the closed cases. 
=== Treatment of Case Materials===
In the following section, it is assumed that all treatments will be carried out by qualified conservators familiar with the materials and characteristics of the objects they are treating. No treatment indications given here can be considered safe for any object without suitable spot testing, careful observations and skilled, judicious application. 
Removing the package from a case: Cases usually have step joints, not mitred joints, and these tend to be weak. If the package is sound (preserver and/or sealing tape intact) it may be possible to use a small suction cup to gently lift the package out of the case. If it is necessary to use a micro-spatula, carefully work the plate out from the top or bottom end. A microspatula with a small section of the tip bent in at 90° may be helpful in lifting the package out of the tray. Keep a firm grip on the edges of the case to counteract the leverage of the micro-spatula. Do not force the package out. It may be impossible to safely remove the package; if this seems to be the case, stop and reassess the procedure. 
Disassembling the package: If an object is not in need of preservation or restoration treatment, it should probably not be disassembled. This is particularly true for those few cased photographs that appear to have their original seals present and intact; there are so few objects in this state that conservators must be wary of obliterating potentially valuable historical evidence. 
If disassembly is to be done, keep the following points in mind: 
*make a detailed record of the configuration of the package as disassembly proceeds;
*make sure you can reassemble the components in the orientation in which you found them;
*minimize the stress on the preserver's flaps and corners by working in stages and using a solid vertical support against the side surfaces of the preserver;
*minimize the risk of damaging the plate by carefully removing the opened preserver from the package components, rather than levering the package components out of the preserver; small clips might be used to keep the plate and mat from sliding against one another during preliminary steps;
*sealing/binding tapes should be removed intact so that they might be reused to reseal the package;
*identify and archive, if possible, any glass or paper components that are permanently removed from the package;
*wear clean gloves when handling daguerreotype, ambrotype or tintype plates; latex examination gloves provide better touch sensitivity than cotton gloves but care must be taken to ensure that talc traces are not present on the glove exterior; 
*never lay a daguerreotype plate face down;
*after examination or treatment, reseal the package (see Resealing entry) and replace the preserver; ensure that the treatment has not increased the size of the package, producing new stress on the joints of the case. 
Leather 
Leather may be gently cleaned with small swabs dampened with a ethanol/water (1/9) mixture. (Some leather colorants may be soluble in alcohol.) 
Areas of lifted leather may be reattached to the wood structure with starch paste, polyvinyl acetate (PVA) emulsion adhesive or with methylcellulose paste (3-4% w/v). Where judged appropriate, skinned and abraded areas may be consolidated with diluted PVA emulsion or methylcellulose paste (approximately 1% w/v) and tinted with acrylic paint. Coatings such as microcrystalline wax or diluted PVA emulsion may be used to modify surface gloss. 
Losses can be compensated with paper infills, either from pulp or from appropriately textured sheets adhered with a diluted PVA emulsion or methylcellulose paste. Paper pulp or tissue can be manipulated and molded while damp to replicate relief elements of the case surface. These can be pre-tinted or tinted with watercolor after application. Watercolor mixed with diluted PVA emulsion may be used to modify gloss. Alternatively, microcrystalline wax or untinted PVA emulsion can be applied over the watercolor to alter the infill gloss. 
After all other structural and cosmetic treatments have been completed, some conservators may sparingly apply microcrystalline wax that is buffed to produce an even surface finish. 
See treatment entry for repairing broken hinges. 
Paper 
Losses to the paper covering on the exterior of a case can be filled with paper sheets or pulp in the same way as losses in leather coverings, as described in the section above. 
Paper mats inside passe-partout daguerreotype packages can be treated as other paper objects, including dry cleaning, washing, bleaching, repairing, infilling, lining and flattening, as required and if possible. 
Deacidification treatments which leave calcium or magnesium residues should be avoided so as not to introduce potentially harmful materials into the sealed package. 
Paper mats for tintypes, if they can be safely separated from the plate, can be treated similarly using the full gamut of paper conservation techniques. 
Decorative paper strips and paper frames used as sealing tapes on passe-partout packages or any damaged original sealing tape can also be treated. Often these tapes will be found to have been split open and inadequately repaired; sometimes later additions of sealing tape will have been applied directly over original tapes. Conventional paper conservation treatments can be used to remove, restore and reuse this original material. 
Lining damaged original paper strips onto a thin Japanese paper or onto lens tissue with dilute starch paste will allow these components to be reused, either alone or over a new sealing tape. 
See treatment entry for repairing broken paper hinges and resealing the packet using original paper tapes. 
Thermoplastic Composite Material (Union case)
Little has been reported about cleaning or repair treatments for this material. B. L. Smith (1994), in a study of these cases, has pointed out some potential problems with aqueous cleaning treatments. She recommends reliance on dry cleaning methods, including brushing, vacuuming and mechanical excavation. 
Smith cites a successful use of 10% Acryloid B-72 in toluene to repair breakage. Losses have been successfully filled with a two-part epoxy putty, Araldite, which can be toned with acrylic emulsion or acrylic resin paints. 
Smith also cites a collector using Arcon 140 epoxy tinted with oil paint to fill losses. 
Glass 
While handling glass objects, always ensure that they are well supported. 
Use a padded board as a work surface. This can be made by covering a piece of heavy cardboard with cotton textile and many layers of lens tissue. The lens tissue can be removed one layer at a time as it gets soiled. 
Noncorroded glass: Undeteriorated but dirty cover glass may be cleaned and reused. (Note that it may be impossible to distinguish dirt from deterioration with certainty.) Begin by brushing the glass surface with a long-haired soft brush. Always brush from the centre of the plate outward. 
Clean the glass with wads of cotton wool or large swabs. Use an ethanol/water mixture or an acetic acid solution for cleaning glass. Ethanol improves the efficiency of cleaning and aids in the evaporation of the water. Once the glass is clean, it should be wiped with lens tissue. To check cleaning, breathe on the plate and watch the evaporation. If the vapor evaporates evenly, the plate is clean. Glass cleaning solutions containing ammonium hydroxide should not be allowed to contact the surface of an ambrotype. 
Corroded glass: Some conservators and conservation scientists advise that cover glass showing signs of corrosion should always be removed and replaced with new glass. Deteriorating glass should not be cleaned and reused as the cleaned, unstable glass will then enter into a new and rapid phase of deterioration.
Others recommend that deteriorated cover glass be retained in place, but only if the object is to be stored in a humidity-controlled area (40-55% RH) and will be regularly monitored. In this case aqueous cleaning should not be done, only dry cleaning, in order to avoid starting a new, rapid corrosion cycle. (Contributor Susan Barger notes that cleaning with vinegar -- 5 % acetic acid solution -- followed by polishing is an acceptable practice for corroded glass that is to be retained.) If the object is to return to an uncontrolled environment or if regular monitoring is unlikely, the deteriorated original glass should be removed and replaced with new glass.
It may be possible to retain a deteriorating cover glass while separating it from the plate and mat below. This can be done by introducing a transparent barrier such as Mylar or new glass. Note that this might accelerate glass corrosion at the interface.
Reverse-painted cover glasses may show paint losses and cleavage, but no glass deterioration; in such cases, the paint can be consolidated and inpainted with acrylic emulsion paints or acrylic resin paints. When reverse-painted cover glass shows evidence of glass deterioration, a copy may be produced on a new glass as a replacement using the paints noted above; spray application of diluted paints using a self-adhesive mask to protect the unpainted aperture produces the most satisfactory result. Where copying or replacement is impossible or undesirable, a transparent barrier may be placed under the deteriorating original cover glass. 
It should be remembered that even the best quality of replacement glass may itself show signs of deterioration ten to twenty years after its installation. This is due to the unfavorable configuration of having sheet glass adjacent to a small enclosed airspace which is the unavoidable geometry of the cased photograph package. Inspection programs to detect glass deterioration are necessary even for objects that have new cover glass. Also, since replacement is not an absolute remedy to the problem, some conservators argue for intermediate or hybrid approaches which maintain the original components together.
If a replacement is to be made, most ordinary modern picture framing glass can be used as long as it is free of flaws and color cast. The edges of newly cut glass should be sanded (use wet/dry sandpaper or a whetstone); this removes the sharp edges that can cut through the sealing tape and provides a better tooth for adherence.
Specialty glass, such as anti-reflection glass, is probably an unnecessary expense because it is not significantly more durable than ordinary picture framing glass. Also, cased photographs require carefully controlled display illumination, so there is little advantage to be gained from anti-reflection glass. Some anti-reflection glass is colorless (for example, Tru Vue - Premium Clear). This might be considered when the slight greenish cast often found in common window glass adversely effects the appearance of the photograph. Polymer glazing materials, such as Plexiglas, should be avoided. These scratch easily and do not provide a barrier to corrosive gases. However, note that some contemporary daguerreotypists use acrylic glazing, rather than glass, in their plate housings. 
All collections of cased photographs should be monitored regularly for glass deterioration. 
When the support glass of an ambrotype corrodes, there is very little treatment that can be done to alleviate the damage caused by the corrosion. 
Ensure that the object is maintained in a stable environment with minimal humidity fluctuation. See Katherine Whitman's section Glass in Photographic Materials for more details regarding glass history, manufacture, and repair. 
Wood 
Broken or detached wooden case components can be repaired using hide glue or PVA emulsion. Repaired joints must be clamped during drying; small frame clamps or elastic bandages, in addition to a variety of small spring clamps, will be useful for this purpose. Missing wooden members can be replaced with balsa wood or with 8-ply matboard, trimmed to fit precisely and covered with paper and finished to match the original case materials. Joints can be reinforced with paper reinforcements applied with PVA emulsion adhesive or methylcellulose paste. 
Trays that have opened corner joints and that cannot be closed around a package that is slightly too large may be modified by adding matboard or balsa shims at the opened joints. These can be covered and finished as noted above. 
Brass 
Surface dirt on brass components may be reduced with dry or damp cotton swabs. It may be possible to wash these components in water containing a surfactant to remove heavier soil accumulation; they must be rinsed and carefully dried after water cleaning to avoid initiating or accelerating corrosion. Mats and preservers were usually varnished with tinted shellac; these coatings may be soluble in alcohol or other organic solvents. 
Corrosion products that project above the surface of the metal as brittle blisters may be reduced mechanically, using sharpened wooden sticks (preferably hardwood) or pointed scalpel blades or other micro-tools. It may be advisable to coat areas treated in this way; consider acrylic resins (Acryloid B-72; B-67; B-48N) or Incralac, which contains benzotriazole (BTA) -- a corrosion inhibitor. 
Inpainting may be done with "metallic" pencils; acrylic paints; gouache paints; acrylic resin Acryloid B-72 or methylcellulose mixed with bronze powders; or acrylic emulsions Rhoplex N580/AC-33 (1/1) mixed with Mica Pigments. An appropriate isolating layer should be used beneath all inpainting. 
Where a burr on the verso edge of the mat aperture has produced scratches on a daguerreotype plate surface, further damage can be avoided by several measures: 
*the sharp edge may be dulled or rolled forward with a stainless steel burnisher;
*a sheet of spacer material can be custom cut and introduced underneath the mat; use one of the thicker nonwoven polyester web materials;
*several thin spray applications of Acryloid B-72 to the sharp edges will even out the surface. 
Broken preservers may be repaired with a viscous Acryloid B-72 formulation (HMG adhesive) and brass foil. The exterior surface of the broken corner is temporarily taped together, then a small L-shaped piece of brass foil is pressed into place on the interior side, molding it into the three-dimensional conformation of the stamped design with a bone folder or other appropriate shaping tool. The reinforcing foil is then removed, coated with the viscous adhesive on the contact surface, pressed into place and allowed to dry. This process can be repeated to provide further reinforcement. 
Textile 
The cushions and retainer strips inside the case may be first cleaned by blowing loose dirt away with a rubber bulb blower or by using a Mini-Vac equipped with a plastic pipette attachment. More solidly adhered debris might be removed using a medium bristle brush. Water treatments are not advised. 
Stained areas on the retainer may be successfully "overpainted" with pastel pencils. 
Missing textile cushions and retainers can be reconstructed using acrylic or cotton velvet, high-quality 2-ply matboard and cotton batting. Such reconstructions should be carried out with the collaboration of a knowledgeable curator or custodian. 
Repairing Broken Hinges 
If the trays are completely detached from each other, begin by lifting the original covering material along the interior and exterior hinge edges. 
Whether the case is covered with leather, cloth or paper, the material is usually very thin and easily torn through. It is important to work slowly to control the lifting. Dampening the material frequently with an ethanol/water (1/1) mixture may help prevent delamination. Once the hinges are lifted, introduce the repair material. 
In choosing the repair material, consider strength and flexibility requirements, and compatibility with the original material. Choices for repair materials include: 
*bookbinders' repair vellum sanded to tissue thickness; 
*lightweight Japanese paper or 40 gsm Silversafe paper (cut with machine direction perpendicular to strip); 
*thin nonwoven polyester web material, such as Cerex or Reemay;
*if the broken hinge is a simple leather strip, consider using a strip of new, properly toned leather as replacement. 
The most common repair adhesives are PVA emulsion (usually diluted), methylcellulose and starch paste. The choice of adhesive depends on flexibility requirements and on the repair material chosen. 
The repair material is cut in strips of appropriate width and adhered to the wooden surfaces. The repair strip is then covered with the flaps of the original covering. Weight the repair after readhering the flaps. 
If both inner and outer hinges are to be repaired, start by repairing the outside hinge, then repeat this procedure for the interior hinge. 
 
Illustrations: Toshiaki Koseki
Prepare infills as outlined in the leather treatment entry and tint the exposed areas of the repair with watercolor, watercolor in dilute PVA emulsion, acrylic emulsion paint (Liquitex gloss medium) or tinted wax. 
Repackaging Plates 
For daguerreotypes, two distinct approaches to repackaging exist. In one approach, the sealed daguerreotype package contains no hygroscopic material, thus avoiding the presence of a reservoir of moisture inside the package that could drive the various processes of metal corrosion. This practice reflects the original format of cased daguerreotypes where no paper products, except the sealing tape, were included in the package. The other approach is to intentionally include a quantity of high-quality unbuffered matboard inside the sealed package (but not in direct contact with the daguerreotype image surface). This acts as a humidity buffer inside the package, helping to dampen relative humidity fluctuations inside the package. This practice reflects the original format of passe-partout packages, which contain substantial quantities of paper, cardboard and adhesives. 
Whatever repackaging method is chosen, it is essential to ensure that all of the package components are well secured and will not slip or shift. 
Mechanical damage due to component slippage is a common phenomenon in cased photographs and avoiding future occurrences should be a major criterion in choosing a repackaging method.
Non-hygroscopic Package
This method uses a moisture-resistant barrier on the back of the package and does not introduce any hygroscopic material inside the package. A 5 mil Mylar backing is cut to be slightly smaller than the plate. If a barrier is required to prevent abrasion of the plate surface (see brass treatment), use a layer of a nonwoven polyester web material. The package is closed with a moisture-resistant sealing tape as described in the treatment resealing entry. This style of repackaging has the advantage of adding little or no extra thickness and allowing the plate verso to be seen without disassembling the package. 
Marvelseal, a nylon/aluminum/polyethylene laminate, has also been used as an impermeable backing, but it lacks the advantage of transparency. If the plate is much smaller than the package, this method is difficult to use. 
Humidity-buffered package variant 
Modify the package described above by including a rectangle of matboard cut to precisely fit between the verso of the daguerreotype plate and the Mylar. 
Use high-quality matboard that does not contain alkaline pH-buffering compounds and that has been conditioned to an appropriate moisture level. 
Use a matboard thickness that will not add significantly to the package thickness if the plate is to be returned to a case. 
Matboard Sink 
This variant is most useful in the repackaging of passe-partout style packages and stereo-daguerreotype packages. A multilayer matboard structure is made that holds the plate in correct register, provides maximum support for all edges and for the plate verso surface, and provides a separation between delicate surfaces and the glazing material. Use rectangles of high-quality, unbuffered 2-, 4- and 8-ply matboard cut larger than the finished package size to create a sink cavity for the plate. Use a layer of a nonwoven polyester web material to provide separation between the plate and any original package components that may cause abrasion or scratches. 
Adhere these layers with 3M Double-sided Tape No. 415, starch paste adhesive, methylcellulose paste or PVA emulsion adhesive. It is essential to add only the minimum possible additional thickness to the package if it is to be returned to a case. 
 
George Eastman House Housing 
The Conservation Department at the George Eastman House has developed an elegant structure for housing unpackaged daguerreotype plates that combines some features of both approaches outlined above. This housing was inspired by a unique metal and paper housing associated with the American daguerreotypist Robert Cornelius. A matboard sink mat is made with cavities for the daguerreotype and for the cover glass. (See drawing on next page.) 
The daguerreotype cavity is slightly deeper than the total thickness of the plate, including its bevelled edges. The cover glass cavity should be the same depth as the glass thickness. A 5-mil Mylar cradle holds the edge of the plate and prevents it from moving inside the slightly oversized cavity or from contacting the inner surface of the cover glass. The cradle is made from two sheets of Mylar. One is cut to the width of the plate and folded at the top and bottom edges to form a Z-shaped spacer or spring; the other is cut to the height of the plate and is folded to form "Z" springs at the sides of the plate. The ends of the Mylar sheets should be trimmed to fit precisely into the spaces of the cover glass cavity. Once the cradle, the daguerreotype plate and the glass are precisely fitted into the matboard sink structure, the glass is sealed to the top surface of the matboard with paper tape. This system can be adapted to include an original brass mat behind the cover glass. The finished package can be easily overmatted and framed for display.
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Illustration: George Eastman House 
Resealing 
Reusing original tapes: This should be done when possible to preserve the original package components. It may be possible to change a deteriorated cover glass by releasing the tape from the front with minimal solvent application, removing the glass, fitting in the new glass and reactivating the original adhesive to secure the new glass. Damage on the original tape can be repaired using conventional methods. If original binding tapes must be removed and replaced with new materials, consider storing the removed tape fragments in the case tray, behind the package. 
Self-adhesive tapes: Many conservators prefer pressure-sensitive tapes for sealing cased photographs because they are easier to handle than paper tapes made with wet adhesives and they do not introduce moisture into the sealed package. Paper tapes such as Filmoplast P-90, Filmoplast P-91 or Filmoplast T (textile carrier) have been commonly used to reseal cased photographs. 
Polyester-backed or Mylar-backed tapes provide some moisture barrier. 
Notable among these are the 3M Polyester Film/Tape No. 850 (Silver), which is thin and flexible. 
It may be preferable to isolate the edge of the daguerreotype plate from contact with the adhesive. This can be done by laying a thin strip of nonadhering material down the centre of the sealing tape. Use 3-mil Mylar, Hollytex, Japanese paper or a thin strip of the sealing tape itself, turned so that its nonadhesive surface contacts the plate edge. See application instructions under "Plain paper tapes" below.
Self-adhesive tapes can be used alone or be covered with the original paper sealing tape that has been removed and treated as described in Treatment: Paper and Tapes and Mats entry.
Original paper seals
These auxiliary paper seals may be adhered with diluted PVA emulsion adhesive, methylcellulose paste or with a mixture of wheat starch paste/methylcellulose/PVA emulsion (3/3/1).
Plain paper tapes: Note that the use of aqueous adhesives may produce an unavoidable exposure of the package components to moisture. Consider using the alternatives described above.
Choose an appropriate paper. Examples are: Renaissance paper; 40 gsm Silversafe; a decorative paper tape, lined onto more stable or stronger paper if necessary. Paper tapes should be cut across the grain (machine direction perpendicular to the length of the strip) to give the maximum strength across the seal.
Choose an appropriate adhesive. Examples are: wheat or rice starch paste; PVA emulsion (undiluted); methylcellulose paste; mixtures of starch paste, methylcellulose and PVA emulsion. Starch pastes should be used stiff and be applied sparingly. (If there is any risk of the adhesive wicking between the package layers, the wet adhesive method should not be used or try using the non-adhesive strip technique described previously.) 
Place one edge of the plate package on the pasted tape and walk the plate around it until the strip is adhered to the edges in a continuous band. A weak clamp applied (with a cushioning barrier) to one edge of the package may help. Trim the excess length away before laying down the last section of the strip; there should be a slight overlap of paper where the ends of the strip come together. Lightly rub the edges to set, taking care not to tear the paper. Pinch the corners so that they come together in a triangle that is perpendicular to the plate package. Cut the triangles with a pair of scissors at a 45-degree angle. Working around the plate, lift one edge of each corner and push the other edge underneath it. This will enable the corners to lay flat. Let the tape air dry for at least one hour before trimming or tinting.
Make the trimming cut with a very sharp scalpel, being careful not to scratch the glass. If the tape is to be tinted, apply the paint before removing the excess strip; the waste paper will act as a guard for the glass and allow the tinting medium to absorb into the cut edge of the tape. When the tape is dry, remove the excess strip.
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==Glossary==
*Alabastrine process -- a variant of the ambrotype process, using mercury chloride bleaching
*Ambrotype -- a collodion silver photograph on glass; a direct positive camera original
*Amphitype -- among other things, a process similar to ambrotype but using albumen
*Binding tape -- an alternate term for sealing tape
*Case -- a hinged box holding an ambrotype, or an American or British daguerreotype
*Clasp -- brass hardware on a case that secures the closure of the hinged case cover
*Collodion -- binder layer of ambrotypes, tintypes, and wet-plate negatives
*Collodion positive -- term used in Britain for ambrotype
*Cover glass -- protective glazing used on daguerreotypes, and some ambrotypes and tintypes
*Cushion -- cardboard, cotton fibre and textile pad fixed to the inside surface of the case cover
*Daguerreotype -- a photograph with silver image particles on a silvered copper plate
*Deliminator -- an alternate term for a metal mat
*Ferrotype -- an alternate term for tintype
*Gilding -- a step in daguerreotype processing in which gold is added to the image particles
*Hinge -- paper, leather or metal attachment between the case cover and tray
*Lacquer -- a pigmented paint layer, used on both ambrotypes and tintypes
*Lampratype -- a variant of the ambrotype process
*Mat -- paper or metal sheet with an aperture cut in its centre
*Melainotype, melanotype -- alternate terms for both ambrotype and tintype
*Package -- plate and housing components forming a sealed unit; may be cased or framed
*Pad -- an alternate term for cushion
*Pannotype -- a collodion positive, similar to a tintype, but on black waxed textile or leather
*Passe-partout (package) -- a daguerreotype housing format common in Europe
*Perfling -- an alternate term for retainer
*Pinchback -- an alternate term for preserver
*Pinch pad -- an alternate term for retainer
*Preserver -- for cased objects: brass foil that is folded around the edges of the plate package
*Relievo -- a variant of the ambrotype, in which the background image areas are scraped away
*Retainer -- velvet and cardboard strip lining the edge of the case tray
*Sealing tape -- strip adhered at the perimeter of a package and holding the components together
*Stereograph -- a two-image photograph which represents its subject three-dimensionally
*Tintype -- a collodion silver photograph on an iron plate; a direct positive camera original
*Tray -- the half of the case opposite the cover, which receives the package
*Union case -- a case made of an early thermoplastic material
==Bibliography==
===General===
*Angelucci, S.; P. Florentino; J. Kosinkova; M. Marabelli. "Pitting Corrosion in Copper and Copper Alloys: Comparative Treatment Tests." Studies in Conservation 23 (1978), pp. 147-156. 
*Austin, Michele C. "An Examination of Daguerreotype Brass Mats." University of Delaware/Winterthur Art Conservation Program, unpublished student research project report, 21 May, 1984. 
*Barger, M. Susan; Deane K. Smith; William B.White. "Characterization of Corrosion Products on Old Protective Glass, Especially Daguerreotype Cover Glasses." Journal of Materials Science 24 (1989), pp. 1343-1356. 
*Brown, Barbara. "Four-flap Enclosure ('Tuxedo' Case) Adapted for Housing Cased Photographs." Austin, Texas: Harry Ransom Humanities Research Center, unpublished presentation, September 1996. 
*Hendriks, Klaus B.; Brian Thurgood; Joe Iraci; Greg Hill. Fundamentals of Photograph Conservation: A Study Guide. Toronto: Lugus Publications, 1991. 
*Hendriks, Klaus B. CCI Notes 16/1: Care of Encased Photographic Images. Ottawa: Canadian Conservation Institute, 1995. 
*Hill, Jo. "Corrosion of Mats and Preservers on Case Objects." University of Delaware/Winterthur Art Conservation Program, unpublished student research project report, May 1991. 
*King, Chris. "My Grandmother Has One of Those -- Daguerreotypes, Ambrotypes, Tintypes -- Their Problems, Processes, and Care." Conference of Students in Art Conservation. April 10-12, 1978. Cooperstown, NY: Cooperstown Graduate Programs, 1978, pp. 82-97. 
*Krainik, Clifford; Michele Krainik; Carl Walvoord. Union Cases: A Collector's Guide to the Art of America's First Plastics. Grantsburg, WI: Centennial Photo Service, 1988. 
*Kusnerz, P.A. "Preservation of Case Photographs." Michigan Museums Review 7, no.4 (1973), pp.7-9.
*Longford, Nicola. "Stamped Vines and Verdigris: Uncasing the Mysteries of the Brass Mat." St. Louis: Missouri Historical Society, unpublished presentation, September 1996. 
*Rempel, Siegfried. "The Conservation of Case Photographs." Archivaria no. 3 (winter, 1976/1977), pp. 103-108. 
*Rinhart, Floyd; Marion Rinhart. "Miniature Cases for Daguerreian Art." In American Daguerreian Art. New York: Clarkson N. Potter, Inc., 1967, pp. 87-91. 
*Rinhart, Floyd; Marion Rinhart. American Miniature Case Art. Cranbury, NJ: A. S. Barnes and Co., 1969. 
*Smith, Brenda Lee. "Photographic Union Cases: The First Plastic Composite." Queen's University Art Conservation Program, unpublished student research report, 1994.
===Daguerreotypes===
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*Barger, M. Susan; S.V. Krishnaswamy; R. Messier. "The Cleaning of Daguerreotypes: I. Physical Sputter Cleaning, A New Technique." AIC Preprints. Washington, DC: American Institute for Conservation of Historic and Artistic Works, 1982, pp. 9-20. 
*Barger, M. Susan; R. Messier; William B.White. "A Physical Model for the Daguerreotype." Photographic Science and Engineering 26, no. 6 (1982), pp. 285-291. 
*Barger, M. Susan. "Robert Cornelius and the Science of Daguerreotypy." In William F.Stapp. Robert Cornelius: Portraits from the Dawn of Photography. Washington, DC: The National Portrait Gallery, 1983, pp. 111-128 
*Barger, M. Susan; R. Messier; William B.White. "Gilding and Sealing Daguerreotypes." Photographic Science and Engineering 27, no. 4 (July/August 1983), pp. 141-146. 
*Barger, M. Susan; R. Messier; W.B.White. "Daguerreotype Display." Picturescope 31, no. 2 (summer 1983), pp. 57-58. 
*Barger, M.Susan; A.P.Giri; William B.White; William S. Ginnell; Frank Preusser. "Protective Surface Coatings for Daguerreotypes." Journal of the American Institute for Conservation 24 (1984), pp. 40-52. 
*Barger, M. Susan; Russell Messier; William B.White. "Nondestructive Assessment of Daguerreotype Image Quality by Diffuse Reflectance Spectroscopy." Studies in Conservation 29 (1984), pp. 84-86. 
*Barger, M. Susan; William F. Stapp. "Daguerreotype: A Precautionary Discussion of Deterioration, Cleaning and Treatment." Preprints. ICOM Committee for Conservation Triennial Meeting, Copenhagen, 1984, pp. 84.14.8 - 84.14.12. 
*Barger, M. Susan; William B.White. "The Optical Characterization of the Daguerreotype." Photographic Science and Engineering 28, no. 4 (July/August 1984), pp. 172-174. 
*Barger, M. Susan; A. P. Giri; W. B.White; T. M. Edmondson. "Daguerreotype Cleaning." Studies in Conservation 31 (1986), pp. 15-28; and "Corrigenda." Studies in Conservation 32 (1987), pp. 141-143. 
*Barger, M. Susan. "Delicate and Complicated Operations: The Scientific Examination of the Daguerreotype." In John A.Wood, ed., The Daguerreotype: A Sesquicentennial Celebration. Iowa City: University of Iowa Press, 1989, pp. 97-109. 
*Barger, M. Susan. "Daguerreotype Care for the Collector." The Daguerreian Annual 2 (1991), pp. 27-32. 
*Barger, M. Susan; William B.White. The Daguerreotype: Nineteenth-Century Technology and Modern Science. Washington, DC: Smithsonian Institution Press, 1991. (This is a fairly complete summary of most of Susan Barger's research on daguerreotypes to 1991.) 
*Bisbee, A. The History and Practice of Daguerreotyping,--. First published, Dayton: L. F. Claflin, 1853. Reprinted, New York: Arno Press, 1973. 
*Boudreau, Joseph. "Color Daguerreotypes: Hillotypes Recreated." In Ostroff, Eugene, ed. Pioneers of Photography, --. Springfield, VA: SPSE - Society for Imaging Science and Technology, 1987, pp. 168, 189-199. 
*Brodie, I.; M. Thackray. "Photocharging of Silver Iodide and Its Relevance to the Daguerre Photographic Process." Nature 312, no. 5996 (20-27 December, 1984), pp. 744-746. 
*Buerger, Janet E. French Daguerreotypes. Chicago: University of Chicago Press, 1989. 
*Daffner, Lee Ann; Dan Kushel; John M. Messinger II. "Investigation of a Surface Tarnish Found on 19th-Century Daguerreotype." Journal of the American Institute for Conservation 35 (1996), pp. 9-21. 
*Daguerre, (L. J. M.) "Practical Description of the Process Called the Daguerreotype --" Translated by J. F. Frazer. Journal of the Franklin Institute 24 (1839), pp. 303-311. 
*The Daguerreian Annual --. Lake Charles, LA.: The Daguerreian Society, 1990 - . 
*The Daguerreian Society Newsletter --. Green Bay, WI.: The Daguerreian Society. 
*Daniels, V. "Plasma Reduction of Silver Tarnish on Daguerreotypes." Studies in Conservation 26, no. 2 (1981), pp. 45-49. 
*Daniels, Vincent. "Advances in the Use of Hydrogen Plasma for Reduction of Silver Tarnish. Treatment of Daguerreotypes." Preprints. 6th Triennial Meeting, Ottawa, 1981. Paris: International Council of Museums Committee for Conservation, 1981, pp. 81/14/20-1 - 81/14/20-5. 
*Edmondson, Thomas M.; M. Susan Barger. "The Examination, Surface Analysis, and Retreatment of Eight Daguerreotypes which were Thiourea Cleaned in 1977." Topics in Photographic Preservation 5 (1993), pp. 14-26. 
*Enyeart, James L. "Reviving a Daguerreotype." The Photographic Journal 110 (September 1970), pp. 338-344. 
*Hardwich, T. Frederick. "On the Theory of the Daguerreotype and Talbotype Processes, Etc." In A Manual of Photographic Chemistry, --. 4th ed. New York: S. D. Humphrey, 1858. 
*Heller, Nancy Joan. "Electrocleaning of Daguerreotypes: Is Metallic Redeposition a Concern?" University of Delaware/Winterthur Art Conservation Program, unpublished student research report, 1988. 
*Hill, Levi L.; W. McCartey. A Treatise on Daguerreotype,--. Reprint of the 1850 ed. New York: Arno Press, 1973. 
*Hill, Levi L. A Treatise on Heliochromy:--. New York: Robinson and Caswell, 1856. 
*Humphrey, S. D. American Handbook of the Daguerreotype,--. First published, New York: S.D.Humphrey, 1858. Reprinted, New York: Arno Press, 1973. 
*Jacobson, Leon; W. E. Leyshon. "The Daguerrian Measles Mystery." Graphic Antiquarian 3, no. 4 (April 1974), pp. 14-15. 
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*Kung, Natasha, Nora W. Kennedy, and Eric Breitung. "Refining the Daguerreotype Package", Abstract in Topics in Photographic Preservation, (2019), p. 236. Presentation at the February 2019 Joint meeting of the American Institute for Conservation - Photographic Materials Group Winter Meeting and International Council of Museums Committee for Conservation, Photographic Materials Working Group, New York, NY, USA.
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*Mustardo, Peter J. "The Daguerreotype's Environment." Topics in Photographic Preservation 1 (1986), pp. 16-22. 
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*Pobboravsky, Irving. Study of Iodized Daguerreotype Plates. Rochester, N.Y.: Rochester Institute of Technology, 1971. 
*Pobboravsky, Irving. "Daguerreotype Preservation: The Problems of Tarnish Removal." Technology and Conservation 3, no. 2 (1978), pp. 40-45. 
*Quintero Balbas, D.; Cattaneo, B.; Cagnini, A.; Belluzzo, P.; Rossi, S.; Fontana, R.; Striova, J. "The Degradation of Daguerreotypes and the Relationship with Their Multi-Material Structure: A Multimodal Investigation." Sensors 2023, 23, 4341. https://doi.org/10.3390/s23094341 
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*Rinhart, Floyd; Marion Rinhart. "Notes on the Daguerreotype Plate." The New Daguerrian Journal 3, no. 2 (1975), pp. 4-7. 
*Rinhart, Floyd; Marion Rinhart. The American Daguerreotype. Athens, GA: University of Georgia Press, 1981. 
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*Schlather, Andrea E., Paul Gieri, Alejandro Manjavacas, and Silvia A. Centeno. Visualizing the Nanoscale: New Developments in the Understanding and Preservation of the Daguerreotype Image. Topics in Photographic Preservation, (2019), Abstract p. 234-235. Presentation at the February 2019 Joint meeting of the American Institute for Conservation - Photographic Materials Group Winter Meeting and International Council of Museums Committee for Conservation, Photographic Materials Working Group, New York, NY, USA.
*Shoemaker, W. L. "Cleaning the Daguerreotype." The Philadelphia Photographer 14 (1877), p. 233. 
*Sobieszek, Robert A., ed., The Daguerreotype Process: Three Treatises, 1840-1849. New York: Arno Press, 1973. (Reprints texts by Gouraud, 1840; Claudet, 1849; Humphrey and Finley, 1849.) 
*Swan, Alice. "Conservation Treatments for Photographs. A Review of Some of the Problems, Literature and Practices." Image 21, no. 2 (1978), pp. 24-31. 
*Swan, Alice. "The Preservation of Daguerreotypes." In AIC Preprints. Washington, DC: American Institute for Conservation of Historic and Artistic Works, 1981, pp. 164-172. 
*Swan, Alice. "Coloriage des Epreuves: French Methods and Materials for Coloring Daguerreotypes." In Janet E. Buerger. French Daguerreotypes. Chicago: University of Chicago Press, 1989, pp. 150-163. 
*Swan, A.; C. E. Fiori; K. F. J. Heinrich. "Daguerreotypes: A Study of the Plates and the Process." Scanning Electron Microscopy. AMF O'Hare, IL: SEM Inc., 1979, pp. 411-423. 
*Wagner, Sarah S. "Some Recent Photographic Preservation Activities at The Library of Congress." Topics in Photographic Preservation 4 (1991), pp. 136-149 (see "Daguerreotype Project Preservation", pp. 143-145). 
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*Watson, Roger C. "Preservation of Daguerreotypes." In Daguerreotype Workbook. Rochester: George Eastman House / International Museum of Photography and Film, 1996. 
*Wei, William (Bill), Ingrid Gerritsen, and Clara von Waldthausen. 2010. Re-examining the (Electro-)Chemical Cleaning of Daguerreotypes: Microscopic Change vs. Macroscopic Perception, in Photographic Preservation, 2011, Volume 14, Article 5 (pp. 24-40); Presented at the PMG session of the 2010 AIC Annual Meeting in Milwaukee, Wisconsin, USA
*Wetzel, Rachel Kay. Working Methods and Scientific Analysis of Robert Cornelius's Daguerreotypes: How a collaborative partnership of conservators, curators, scientists, and artists help to collectively broaden the understanding of the history of early photography in America, Topics in Photographic Preservation, (2019), p. 217-233. Presentation at the February 2019 Joint meeting of the American Institute for Conservation - Photographic Materials Group Winter Meeting and International Council of Museums Committee for Conservation, Photographic Materials Working Group, New York, NY, USA.
===Ambrotypes and Tintypes===
*Archer, Frederick Scott. "On the Use of Collodion in Photography." The Chemist 2 (March 1851), pp. 257-258. 
*Baas, Valerie. "Conservation of Tintypes." American Institute for Conservation - Photographic Materials Group, 2nd annual meeting, Milwaukee, 1982, unpublished presentation. 
*Baas, Valerie. "The Treatment of a Flood Damaged Ambrotype." American Institute for Conservation -- Photographic Materials Group, 3rd annual meeting, Chicago, February, 1983, unpublished presentation. 
*Barger, M. Susan. "Characterization of Deterioration of Glass Supported Photographic Images." Printing of Transcript Summaries. Second International Symposium: The Stability and Preservation of Photographic Images. Springfield, VA: Society of Photographic Scientists and Engineers, 1985, pp. 134-147. 
*Barger, M. Susan. "Deterioration of Glass-supported Photographic Materials." New Directions in Paper Conservation: IPC Tenth Anniversary Conference. Oxford: The Institute of Paper Conservation, 1986, pp. D132-D133. 
*Brown, Floyd B.; Harry C. Burnett; W. Thomas Chase, et al. Corrosion and Metal Artifacts -- A Dialogue Between Conservators and Archaeologists and Corrosion Scientists (NBS Special Publication No. 476). Washington, DC: National Bureau of Standards, 1977. 
*Burgess, Nathan G. The Ambrotype Manual. New York: Daniel Burgess and Son, 1856. 
*Davis, Nancy. "Tintypes: Preliminary Research and Testing." Art Conservation Training Programs Conference, May 1-3, 1983. Cooperstown, NY: State University College of New York at Buffalo, 1983, pp. 13-28. 
*Estabrooke, Edward M. The Ferrotype and How to Make It,--. First published, Cincinnati: Gatchel and Hyat, 1872. Reprinted, Hastings-on-Hudson, NY: Morgan and Morgan Inc., 1972. 
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*Hannavy, John. "The Magnificent Ambrotypes." The British Journal of Photography (20 February, 1976), pp. 153-155. 
*Heighway, W. "The Ferrotype." The Practical Photographer 3, no. 7 (1879), pp. 686-688. 
*Humphrey, Samuel D. A Practical Manual of the Collodion Process, Giving in Detail a Method for Producing Positive and Negative Pictures on Glass and Paper. New York: Humphrey's Journal Printer, 1857. 
*"Lessons on Colouring Photographs: Colouring Positives on Glass." The Photographic News 1 (November 26, 1858), p.138, et seq. 
*Logan, Judy. CCI Notes 9/5: Tannic Acid Treatment. Ottawa: Canadian Conservation Institute, 1989. 
*"The Lowly Tintype." The British Journal of Photography (26 December, 1975), pp. 1168-1170. 
*Maurice, Philippe. "History, Identification, Deterioration Characteristics and the Preventive Care of Collodion and of Gelatin-emulsion Ferrotypes." Abstract, Environnement et conservation de l'écrit, de l'image et du son. Actes . . . 16-20 mai 1994. Paris: Association pour la Recherche Scientifique sur les Arts Graphiques, 1994, pp. 254-255. 
*McCabe, Constance. "Preservation of 19th-Century Negatives in the National Archives." Journal of the American Institute for Conservation 30, no. 1 (Spring 1991), pp. 41-73. 
*McCormick-Goodhart, Mark. "Research on Collodion Glass Plate Negatives: Coating Thickness and FTIR Identification of Varnishes." Topics in Photographic Preservation 3 (1989), pp. 135-150. 
*McCormick-Goodhart, Mark. "The Multilayer Structure of Tintypes." In 9th Triennial Meeting, Dresden, German Democratic Republic, 26-31 August, 1990: Preprints. Volume 1. Los Angeles: International Council of Museums, Committee for Conservation, 1990, pp. 262-267. 
*McCormick-Goodhart, Mark H. "An Analysis of Image Deterioration in Wet-Plate Negatives from the Mathew Brady Studios." Journal of Imaging Science and Technology 36, no. 3 (1992), pp. 297-305. 
*McCormick-Goodhart, Mark H. "Glass Corrosion and its Relation to Image Deterioration in Collodion Wet-Plate Negatives." In The Imperfect Image: Photographs, Their Past, Present and Future. Conference proceedings. London: The Centre for Photographic Preservation, 1992, pp. 256-265. 
*Moor, Ian. "The Ambrotype -- Research into Its Restoration and Conservation -- Part 1." The Paper Conservator 1 (1976), pp. 22-25; ". . . -- Part 2." The Paper Conservator 2 (1977), pp. 36-43. 
*Newhall, Beaumont. "Ambrotype: A Short and Unsuccessful Career." Image 7, no. 8 (October 1958), pp. 171-177. 
*Norris, Debbie Hess. "Ambrotype." University of Delaware/Winterthur Art Conservation Program, unpublished class notes, 1989. 
*Norris, Debbie Hess. "Tintype." University of Delaware/Winterthur Art Conservation Program, unpublished class notes, 1989. 
*Pelikán, J. B. "Conservation of Iron with Tannin." Studies in Conservation 11, no. 3 (August 1966), pp. 109-114. 
*Peyton, Michael. "Tintype and Its Treatment." University of Delaware/Winterthur Art Conservation Program, unpublished student research project, May 1991. 
*Rogge, Corina E. 2014. "The varnished truth: The recipes and reality of tintype coatings." Journal of Cultural Heritage Volume 15, Issue 1, Pages 57-63. https://doi.org/10.1016/j.culher.2013.02.002
*Trask, Albion K. P. Trask's Practical Ferrotyper. First published, Philadelphia: Beuerman and Wilson, 1872. Reprinted in Sobieszek, Robert A., The Collodion Process and the Ferrotype: Three Accounts, 1854-1872. New York: Arno Press, 1973.
Page information
:Date initiated: September 1998 
:Contributors for wiki version: Luisa Casella, Amanda Maloney, Stephanie Watkins
Printed version 1998
:Compiler: John P. McElhone
:Contributors: Gary Albright, M. Susan Barger, Valerie Baas, Lee Ann Daffner, Deborah Derby, Tom Edmondson, Monique Fischer, Chris Foster, Lynne Gilliland, Marion L. Hunter, Jr., Wayne King, Barb Lemmen, Mark H. McCormick-Goodhart, Angela Moor, Ian Moor, Peter Mustardo, Debbie Hess Norris, Nancy Reinhold, Andrew Robb, Elena Bulat, and Annabelle Chabauty.
:Copyright: The Photographic Materials Conservation Catalog is a publication of the American Institute for Conservation of Historic and Artistic Works. The Photographic Materials Conservation Catalog is published as a convenience for the members of the Photographic Materials Group. Publication does not endorse nor recommend any treatments, methods, or techniques described within the chapter.
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