DEVELOPMENT.
The print being ready for development, we prepare two dishes of cold water, one dish of five per cent. Alum Solution, a tank or basin of hot water about ioo° F., a squeegee and squeegeeing board. Taking a piece of the single transfer paper, rather larger than the print, we immerse it in one of the dishes of cold water for a few minutes. (Whatman and other rough drawing papers should soak for hours, or else be placed in the hot water developing tank for half an hour before use.) The printed tissue is taken from the frame and placed in the dish of cold •vc ater which contains the transfer paper, bubbles being carefully avoided. It usually commences to curl up and then gradually unfolds itself again. When nearly unfolded it should be brought into position, film downwards into contact with the prepared surface of the transfer paper. Lifting both tissue and transfer paper by the one edge, drag them out of the water over the end of the dish and lav them " tissue " side uppermost on the squeegeeing board. Now apply the squeegee vigorously to the back of the tissue in order to expel all the water between the two surfaces. The transfer paper with the adhering tissue is now gently lifted and placed between blotting boards and kept under slight pressure for about twenty minutes. At the end of this time, the transfer paper with the adhering tissue is placed in the tank of hot water at too° F. In a few minutes we shall see small quantities of
soluble gelatine exuding round the edges of the tissue. We now take one corner of the tissue and lift it right away from the transfer paper. Unless it comes quite easily and without force, it should be allowed to soak longer. The tissue being removed, a dirty mass is seen on the single transfer paper. All we have to do is to leave this mass with the hot water till development is complete. It is well to have a sheet of zinc or glass on which to support the picture during this operation, or the paper support may get damaged. Errors of exposure may be partially compensated at this point. Over exposed prints may be reduced by raising the temperature of the hot water to 12o° or 130°F ; while under-exposed ones should be left to automatically develop, face downwards, at a temperature of 9o°F. When the print is developed, it only requires a rinse in cold water, immersion in the 5% Alum Solution for io minutes to harden the film and remove the bichromate salt, a final wash to remove the alum, and the print is then hung up to dry bv means of clips. When dry the prints may be mounted with any good mountant or starch paste.