TEMPORARY SUPPORT This is used in carbon printing for the double transfer process ; known also as a " flexible support." Its purpose is to hold the carbon film during development, etc., until ready for the second transfer to the final support. The flexible temporary support is a paper coated with a mixture of lac and gelatine that has been rendered quite insoluble ; and, after coating, the paper is rolled under heavy pressure, so as to present a fine, smooth, and semi-glossy sur face. The temporary support is prepared for use by rubbing over with a waxing solution (white wax dissolved in turpentine) ; after allowing two or three hours for the turpentine to evaporate, the support is ready for use in exactly the same manner as single transfer paper. After the flexible support has been soaked for a few minutes in water, the exposed print is squeegeed to the prepared surface; and after development, washing and drying, a piece of double transfer paper is squeegeed to the print. When thoroughly dry, the double transfer
paper holding the film firmly may be pulled away from the temporary support, the surface of which is left quite clean. Before using again the flexible temporary support requires re waxing. When using this support a longer im mersion in the alum bath is necessary than for ordinary single transfer paper.
In addition to the flexible temporary support commonly used in the carbon process, a piece of matt-surfaced opal glass is sometimes used when it is desired to obtain prints with a matt surface instead of the semi-gloss imparted by the flexible paper support. This opal glass is prepared by waxing, and it is used in exactly the same manner as the flexible support.