fearin' disappearin'

February 10, 2009 4:31 PM

Casein/Gum printing: How long will an unwashed print last?

I'm printing from digital negatives onto paper coated with potassium dichromate and casein by exposure to sunlight. The procedure is similar to gum, but the result is quite different.

I get crisp, pretty prints, but when I fix or develop them (fixer is water, developer is water with a hint of ammonia), they smudge and change into undesirable colors.

So, if I don't fix the print, and leave it in a UV-safe place for some time (how long?), will the emulsion lose its sensitivity to light? Or will the image still steadily / rapidly erode upon further exposure?

posted by pita to Media & Arts (2 answers total)

My only experience with light sensitive emulsions is screen printing, so this may be incorrect...

In screen printing you coat a screen with a liquid emulsion that is light sensitive. You let the emulsion dry in a dark UV free area for 24-48 hours. Then you use the screen. I have been told if you let the screen dry for months it is almost completely desensitized to light, so it may be the if you dry the print _very_ thoroughly it will not be sensitive to UV, but I might be completely wrong.

You might also try developing the images with ammonia fumes. Hopefully it will stop some of your smudging. Put enough ammonia into a shallow tray to cover the bottom then put a mesh over the tray and lay your print on top of the tray.

You might also take a look at this article on alternativephotography.com.

I don't have a definitive answer, but maybe one of these ideas will point you in the right direction.
posted by gregr at 7:17 PM on February 27, 2009

Also check this out.
posted by gregr at 7:20 PM on February 27, 2009