Tanning Developers

some use photography to take them into the world. others take the world into photography.
I take photography away from the world. the using excuse

Dye transfer works because …

differing thickness of gelatin gives different amounts of dye to transfer from the “matrix” to the “blank.” The gelatin of the emulsion is the same thickness before it is exposed and processed, developed. After development the emulsion is “washed off” providing a relief image. Soft gelatin washes off, melts, at 90F. To maintain an image means hardening the image forming gelatin. This is done by using a “tanning developer.” Tanning being the action of hardening gelatin.

The first versions of imbibition printing, wash-off relief, used the principle of a tanning bleach such as a dichromate. Dichromate systems were not as sharp as tanning developer systems, so dichromate methods were discarded before 1950.


  • Mees and James, The Theory of The Photographic Process, 1966, p.304
  • US 2,415,666
  • US 3,293,035
  • US 3,746,544