Enamel and Ceramic Photographs Enamel Collodion
" Modern Dry Plates," Eder, Pritchard & Wilmer: London, 1881, Piper & Carter.
Enamel and Ceramic Photographs. Photographic images may be vitrified on porcelain and coated with a porcelain glaze, which makes them permanent as against fading. Enamels are usually prepared on small copper plaques, which are coated with a special material, which may practically be considered to be very soft milk-white glass, and by no means so unalterable as a true porcelain. Metal plaques already prepared can be obtained commercially. On these an image is laid and fired. There are several processes - (a) the substitution process, (b) the powder process, (c) the pigment or carbon process, (d) the collotype process. For the substitution process a collodio-chloride printed-out positive is prepared and fixed. The image is toned with platinum, gold, palladium, iridium, or a selected mixture. The positive is then stripped, transferred to the plaque, and carefully smoothed out, and then fired, coated with glaze, and retired. The powder process is the preparation of a positive by the powder or du'sting-on process on a sheet of glass, coating it with collodion, stripping, and transferring to the plaque, and firing. The pigment process is merely a modification of the carbon process, gum arabic instead of gelatine being sometimes used as the material; it is transferred and fired. The collotype process is sometimes used for preparing the image, a special ink being used and the print being on litho-transfer paper, from which it is transferred to the plaque. It is impossible to enter fully into the subject, and enamel or ceramic processes are very little used at the present day. Mr. Grundy, of Derby, has cleverly applied the principle of multiple impression to collotype work on tiles. The collotype platens inked with a fatty ink containing an ordinary underglaze pottery colour, and impression after impression is made on the unglazed tile; suitable precautions being taken to keep exact register. The tile is then fired and glazed like an ordinary piece of pottery. (See Collotype.) For an account of the pepper-type process and its application to enamel photography, see The Amateur Photographer, July 22nd, 1898, p. 574. A list of books on photography in vitrifiable colours is given under the heading, Glass, burnt in Photographs upon.
Enamel Collodion. See Enamelling Prints below.