U of S | Mailing List Archive | alt-photo-process-l | Re: Gum Humidity Question

Re: Gum Humidity Question

"Spontaneous hardening in the dark"?

I work habitually in the 20's here in Madrid. In full summer around 20% or less and right now 29%. The good thing is that everything dries very fast. The bad thing is that coating must be very fast too. Sometimes I just cannot finish the coat before everything is too dry to go on. But even so not everything is lost since I multi-coat anyway, so in the end the image evens out. The wonderful thing is that I can usually expose some 15 minutes after coating, or even less.

I should really experiment again with humidifying the paper before coating. I think Katherine did that with good results. I had spots in the image afterwards, but I only tried with one paper.

Tom Sobota

Christina Z. Anderson wrote:
Chris, I'm curious why you refer to this as "spontaneous hardening" rather than "dark reaction." Dark reaction has an even steeper relationship to humidity than speed of the light reaction does; for gum the relationship is close to vertical, for this reason I never let coated paper sit around in my humid environment.
Only because I am STILL trying to come up with a witty comeback to Mark Nelson's saying he experienced this sometimes.....