Crystoleum

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Page Information	Page Information
Date initiated 	December 2021
Compiler 	Anna Seweryn
==Crystoleum==
===Historical Facts===
The Crystoleum technique was popular between 1880-1910.  This process was based on a technique called mezzotint painting, that was used in the 18th century to hand-color engravings. 
===Identification Characteristics===
Crystoleum is a photographic technique in which the means used are intended to create an impression of color through the use of coloring and retouching of a monochromatic photographic image made of silver particles. Usually in this technology an albumen print is used. The print must not be too dark. The print is set from the image side (face down) on the cylindrically profiled glass using a binder (typically starch, gelatin, wax, or mixtures of these ingredients). Then, after drying the binder, the paper base is removed in a mechanical way using fine-grained sandpaper, which allow to obtain a transparent image. Before removing the paper backing, the surface of paper is rinsed with warm water. To make the albumen image layer more transparent, it is impregnated with oil, wax, or varnish. This process require heating the entire photograph, which allows the substance to migrate through the image layer to the glass plate. Immediately after this process, an object is laid on a cold metal plate or stone for quick cooling. After the binder is dried, the photograph is retouched and hand-colored. As the layer of the painting was saturated with a hydrophobic substance, oil paints were recommended for retouching. The recommended pigments were: flake white, vermilion, yellow ochre or cobalt. After finishing coloring the image layer, the reverse side is secured with another piece of glass, profiled identically to the image layer carrier. Sometimes at the edges of the object, between the two glass panes, paper strips were inserted, which ensured the appropriate distance for the image layer. Later the colored background is applied to the reverse to give the monochromatic image realistic colors. The background is made on a paper base, most often with the use of oil paints, temper or in the pastel technique. All elements are connected to create an integral object and protect the whole against mechanical, physical and chemical damage (with paper borders or/and with a metal frame). This technique can be modified in various ways, e.g. the colored background can be directly painted on the second (cover) glass, The print may be colored on the face side before being adhered to the glass base.
Typical features of this technique are the muffled color and the profiled glass pane (oval or rectangular) on which the photographs is deposited from the image side. Apart from that, Crystoleum has the characteristics of its components such as the albumen print (see: albumen print). When the object is disassembled we can also see a coloured background made in a schematic way. 
As technique that uses a similar effect and materials to Crystoleum the chrysolotype can be considered, but it is technologically simpler. In this technic the photographic print is filtered with oil and varnishes and painted directly from the reverse with oil paints, which gives the image a shading effect.
====Image material====
The quintessential crystoleum technique is a photographic image transferred onto glass from a paper substrate. Typically, monochrome photography was used for this purpose, where the image is composed of silver particles (albumen print). 
====Color====
The color of Crystoleum is a direct result of the type of paints used for coloring of black and white image and where the paint is applied. When colors are applied to the face of a photograph before it is placed on the glass, the colors may be perceived as very intense. In case of applying paint on the back of the photograph and on the added background, the color is less legible and the contours of particular color areas are blurred. The type of binder used in the production of the photographic image itself also has a minor color significance. 
====Support====
The base of Crystoleum is a cylindrically profiled glass pane. In the case of the oval glass, it was obtained from a section of blown glass sphere and thus in its structure we can find many imperfections such as uneven glass thickness, air bubbles and waves on the surface. The technological process of making cylindrical glass was so complicated that it is difficult to obtain identical two glass sheets. Therefore, the back ( protection) glass pane may be slightly different from the glass pane which is the image carrier.
===Conservation===
The conservation processes undertaken will depend on the state of preservation of the object and will be driven by the ability to access the various layers of the photograph. The most frequent damages to photographs made in the Crystoleum technique include mechanical damage to the glass base as well as the delamination of the photographic image layer. 
Surface Cleaning
The face and at the same time the base of the object is a glass plate which can be cleaned like glass in other photographic techniques, both mechanically and chemically (water-alcohol solutions, see: Preservation of Glass in Photographic Materials). During the cleaning process one should pay special attention to the edges of the object in order, for example, not to wet the paper mounting tapes responsible for the sealing of the object. 
Image Layer Consolidation
If the image layer detaches from the base, reattaching it to glass should be considered.  Before proceeding, the surface of the glass plate should be cleaned of any residual wax-resin or other binder compound. During the process the most important is to obtain a uniform surface of the image, minimize the presence of air bubbles between the surface of the image and the glass and good adhesion of the binder ( ex. photographic gelatin, microcrystalline wax and starch paste) to both the image layer and the glass. 
In a situation where there is wax in the structure of the object, adhesives based on aqueous solutions would not be effective when used in the conservation process. The original wax layer on the photographic image layer can be uneven and may require mechanical adjustments. The photograph should be stabilized face down on a glass substrate and subjected to a heating process (to reactivate the original binder). The object can be heated using tacking iron and Japanese tissue paper and Melinex to protect the surface. A tacking iron should be led from the center of the object to the edge to bring out possible air bubbles to the outside. The temperature should be gradually increased until the wax activation temperature is reached. If not enough of the original wax-resin compound is available, a a modern substitute (ex. microcrystalline wax) can be add to the object's face. After the heating process, to ensure rapid concentration of the wax and prevent air bubbles, photographs should be set aside on a cool surface or in a cool environment.
During the entire conservation process the most significant risk is associated with the presence of a glass base. If it is damaged, obtaining a similarly profiled glass would probably be impossible, and damage could be possible due to the pressure and temperature change applied in the process.
Glass Replacement/ Addition of Cover Glass and Re-sealing
Due to the unusual form of the glass, it may not be possible to replace the damaged glass pane with one identical to the original, and the damaged glass pane, if broken or cracked, should be restored see: Preservation of Glass in Photographic Materials).
===Housing and Storage Considerations===
When considering ways to preserve the object, given the unusual form of the object, it may be necessary to make a individual housing for the photograph.
Due to the use of wax-resin compounds in the production of Crystoleum, storage of this type of photograph in reduced temperature parameters is not recommended. Low temperatures can result in crystallization of the wax, loss of adhesion of the image layer to the glass and its delamination. 
===References===
Crystoleum in The Focal Encyclopedia of Photography, 4th edition, 2007
Brett Payne, The Crystoleum: Bringing the Art of Photo Colourisation into the Home, http://photo-sleuth.blogspot.com/2011/10/crystoleum-bringing-art-of-photo.html
Anon (1896), A Lesson in Crystoleum Painting (by Cigarette), Otago Witness, 27 August 1896, p.42, Courtesy of Papers Past, http://freepages.rootsweb.com/~brett/genealogy/photosleuth/otagowitness18960827.gif
Crystoleum: Including All the Improvements and Practical Instructions for Acquiring this Popular Art Perfectly, with Full Information on the Method of Mixing and Applying the Colors, Caspar's Original Crystoleum Company, 1883
Heinz K. Henisch, Bridget A. Henisch, The Painted Photograph 1839-1914, Origins, Techniques, Aspirations, the Pennsylvania State University Press, University Park, Pennsylvania 1996
===Further Reading===
Viviana Goggi, Martina Trento, BRITTLE MEMORIES. Case study of a broken photographic crystoleum in Colour Photography and Film: Sharing knowledge of analysis, preservation, conservation, migration of analogue and digital materials – 2021: Conference Proceedings, DOI: https://doi.org/10.23738/RCASB.001
Anna Seweryn, Color on glass-about conservation and preservation projects of Crystoleum, Autochromes, Agfa  Color Plates and  Dufay/Dioptichrome Plate   photographs (case studies) in Colour Photography and Film: Sharing knowledge of analysis, preservation, conservation, migration of analogue and digital materials – 2021: Conference Proceedings, DOI: https://doi.org/10.23738/RCASB.001
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