Bromoil is a pigment process devised by C. Welbourne Piper and E. J. Wall and revealed in 1907. It has appealed both to makers of first-class prints, and also to the most saccharine pictorialists; it was known by its detractors as ‘muck spreading’. It enjoyed a considerable revival in the late 20th century, though its heyday was the 1920s and 1930s.
A bromoil ‘matrix’ is made by treating a conventional bromide print with a dichromate bleach. This removes the halide image but hardens the emulsion in proportion to the density of the silver image. A greasy ink is then applied to the damp matrix, usually with a special brush made of bear hair, cut on a slope: purists recoil from the use of a roller. A dabbing or ‘hopping’ motion adds ink, while a brushing motion removes it: considerable control is possible. The softer the gelatin, i.e. the more water it contains, the less ink it accepts, on the simple principle that oil and water do not mix.
Some modern papers are more suitable for bromoil than others, though, contrary to widespread belief, some variable-contrast papers and some supercoated papers may be used. The ideal bromide print (before bleaching) is slightly lacking in contrast, but of greater than usual density.
The life of a bromoil print is limited principally by decay of the gelatin or the support. For bromoil transfers, the image is printed laterally reversed, inked up, then transferred to plain paper with the aid of an etching press or similar: this is one of the most archivally permanent forms of print.
— Roger W. Hicks
