Imbibition Process

(Russian gidrotipiia, hydrotyping), a photographic method, based on the absorption process, of making color pictures using water-soluble dyes. It is essentially a subtractive method of three-color printing using colored gelatin reliefs (matrices).

In the imbibition process, three color-separated matrices are obtained by a chemical-photographic process in which films covered with thin, light-sensitive gelatin layers are first exposed through a colored negative picture and three filters in turn (red, green, and blue-violet). Then each matrix is colored with a water-soluble dye using the color complementary to the color of the filter that produced the matrix. From matrices having blue, purple, and yellow colors successive contact prints are made (imbibition dye transfer) on a paper or film coated with a thin gelatin layer that has been previously moistened to ensure diffusion of the dye from the matrix into the take-up layer. After three accurately registered transfers from the matrices to the same layer, a colored positive image is obtained. More than 100 prints can be made from one set of matrices by repeated dyeing. The imbibition process is of particular importance as a method for the mass printing of colored moving picture films.