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Article: Reflections on the Material History and Materiality of Photographic Gelatin Author(s): Clara von Waldthausen Topics in Photographic Preservation, Volume 16. Pages: 347-359 Compiler: Jessica Keister © 2015, The American Institute for Conservation of Historic & Artistic Works. 1156 15th St. NW, Suite 320, Washington, DC 20005. (202) 452-9545, www.culturalheritage.org. Under a licensing agreement, individual authors retain copyright to their work and extend publication rights to the American Institute for Conservation. Topics in Photographic Preservation is published biannually by the Photographic Materials Group (PMG) of the American Institute for Conservation (AIC). A membership benefit of the Photographic Materials Group, Topics in Photographic Preservation is primarily comprised of papers presented at PMG meetings and is intended to inform and educate conservation-related disciplines. Papers presented in Topics in Photographic Preservation, Vol. 16, have not undergone a formal process of peer review. Responsibility for the methods and materials described herein rests solely with the authors, whose articles should not be considered official statements of the PMG or the AIC. The PMG is an approved division of the AIC but does not necessarily represent the AIC policy or opinions. Reflections on the Material History and Materiality of Photographic Gelatin Clara von Waldthausen Excerpts from an article published in the PhotoResearcher 25 Abstract This paper discusses the material history of photographic gelatin and argues that gelatin’s material agency, or material characteristics, has a direct link to the employment of gelatin in photography. A distinction between the types of gelatin such as size, glue, consumption grade gelatin is briefly discussed and the history and manufacturing of photographic grade gelatin is contextualised. The progression of the implementation of gelatin for photographic purposes in the nineteenth and twentieth centuries is illustrated and the physiognomies that support gelatin emulsion making are explored. Finally this paper illustrates the relationship between distinctions in the material characteristics of various gelatin photographic papers, and the role that these play in photo history and in the marketplace. Brief History Gelatin, known as animal or hide glue, has a long tradition in the arts, crafts and furniture making in many parts of the world, and has been used from at least the nineteenth century for domestic purposes such as cooking and recipes for stocks, aspics, custards, marmalades and jellies can be found in 19th Century cookbooks such as the Carolina Housewife.1 The employment of gelatin which is obtained by boiling animal hides, hoofs, horn, bones and other cartilage-like animal parts dates back 3500 years to when the Egyptians used gelatin for binding pigments and building coffins for the Pharaohs.2 It is probable that gelatin’s use is even older however the focus of this paper is gelatin in photography, and as such, its ancient history is beyond the scope of this paper. In the middle ages we can find gelatin referenced in art sources such as the manuscripts of Jehan Le Begue, who mentions boiling parchment clippings to make glue or size for paper, parchment, cloth and wooden panels in order to draw better on them.3 Other manuscripts on art and painting mention sizing the canvas or wood panel prior to painting on it.4 In fourteenth Century Europe animal glue (gelatin) was introduced as sizing agent in manufacturing paper.5 Thomas Lambert defined sizing in a publication from 1905, as “undried glue that exists as a tremulous jelly, possessing all the adhesive properties of the latter, but in a much less concentrated form.”6 Size is essentially a bye-product in the manufacture of glue and gelatin, and used in “…calico- printing, by painters, decorators, and in the carpet, straw-hat box, wallpaper and other trades.”7 Consumption gelatin and isinglass were purer forms of glue used in the nineteenth century primarily for culinary purposes, to provide firmness to a dish.8 Gelatin-based products like liquorice and lozenges were made in the same factories where gelatin was manufactured. Use of Gelatin in Photography One of the great attractions of gelatin is its physiognomy. Gelatin is transparent. It dissolves in hot water and gels into a clear film upon cooling. It swells in cold water and holds up to four times its own weight, and when dry it is a rigid yet flexible film. These characteristics, together Topics in Photographic Preservation, Volume Sixteen (2015) 347 von Waldthausen, C. C. Photographic Gelatin with its adhesive properties, are what initially attracted photographic manufacturers and what makes gelatin the material of choice in the implementation of photographic emulsions. The history of the use of gelatin in photography originates in England, with William Henry Fox Talbot, inventor of paper photography. In 1852 Talbot began employing gelatin in his photographic engraving process where a steel plate is coated with gelatin “that is strained when hot, through linen cloth to purify it.”9 That Talbot stressed the need for filtering suggests the desire for a purer form of gelatin than was commonly available at that time. In one of Talbot’s letters he makes reference to the use of gelatin to size paper in his Polytype process.10 On December 24, 1842, Antoine Francois Claudet writes and asks Talbot if gelatin-sized paper meets his (Talbot’s) approval in printing with the Calotype process.11 Although a reply to Claudet’s question cannot be found amongst these letters, Professor Bertrand Lavédrine mentions in his publication Photographs of the Past: Process and Preservation, that Talbot recommended paper to be coated with an extra coat of gelatin prior to sensitizing so as to produce better image results.12 Reference to the use of gelatin as finishing technique or coating, can be found in E.G. Heineken’s excerpt from the Journal of the Photographic Society of London. Heineken recommends coating gelatin onto the paper photograph after printing, to achieve a high gloss.13 Gelatin was furthermore used in various pigment processes such as the carbon process introduced by Alphonse Poitevin in 1855 and improved by Swan in 1866 and in the photomechanical Woodburytype process developed in 1864. During the first 75 years of the nineteenth Century only technical grade and consumption grade gelatin existed. George Nelson’s consumption gelatin patented in 1837 appears to be the purest form of gelatin available at the time and references to its use in photography can be found in the Photographic News for making glass plate negatives.14 In 1871 Richard Leach Maddox published his experiments using gelatin as a “dry” binder, or emulsion, for the light sensitive silver salts on glass plate negatives. Maddox used George Nelson’s fine culinary gelatin for his experiments on glass plate negatives. He claimed it was its transparent quality that made gelatin a useful binder for lantern slides and sensitive plates.15 With the invention of the gelatino- bromide emulsion in 1873, by J. Burgess, marketed as an emulsion that had to be coated onto the glass plate by the photographer himself, and the manufacturing of ready-made dry gelatino- bromide plates by the Liverpool Dry Plate Company in 1874, an alternative to the wet collodion process was offered.16 Finally, in 1875, the editor of the The British Journal of Photography, recommends Nelson’s gelatin for “developed plain paper.”17 It isn’t until the late 1870’s however that gelatin specially made for photographic purposes was manufactured. In 1877, the first references to photographic gelatin are for Nelson’s No. 1 Photographic Gelatin.18 Although published evidence was not found, other gelatin factories probably started producing photographic grade gelatin by the mid 1890’s or at the turn of the Century.19 The J and G Company made Cox Gelatin as early as 1845 and references to Cox gelatin such as used by “enamelling” photographs are found in photographic literature as well.20 The Knox Company in the United States was founded in 1890 and it is not unthinkable that these companies saw an opportunity for producing gelatin for the up and coming photography market. Topics in Photographic Preservation, Volume Sixteen (2015) 348 von Waldthausen, C. C. Photographic Gelatin Manufacture of Photographic Gelatin In 1840, Nelson published his improved and patented method of preparing his gelatin, in Mechanics Magazine. In the publication he mentions that he takes cuttings from hides and skins ‘as glue pieces are commonly made of’ and makes two grades of gelatin with them. The first grade, which is purer, and is later used for photographic purposes, is made via an alkaline method using caustic soda and lime. Once the skins are soft they are washed with cold water for 6 or 7 days and briefly exposed to ‘sulphuric acid gas’, and heated until all are dissolved. Then the mixture is strained of the ‘residuum’ and left in heated vessels to clear. A second grade of gelatin in which the ‘residuum’ is mixed with sulphuric acid is also made.21 Nelson’s patent does not discuss photographic gelatin as this wasn’t produced until the late 1870s but From "ABC of Modern Photography" similarities between photographic gelatin and Nelson’s W K Burton 1884 first grade are discussed below. Similarly to Nelson’s patent, gelatin in the 20th Century is made in similar ways: an acidic (type A gelatin) and an alkaline (type B gelatin) method. Type A gelatin is made from pork skins and Type B gelatin, under which photographic grade gelatin falls, is made from beef hides.22 The biggest difference in the modern manufacture of photographic gelatin after 1950 is that it is made mainly from bones (instead of hides). Type B gelatin is very similar to the way Nelson produced his purer grade.

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