U of S | Mailing List Archive | alt-photo-process-l | Re: Measuring humidity

Re: Measuring humidity

On Sep 29, 2006, at 7:38 AM, Christina Z. Anderson wrote:

My temps were consistent in SC but the humidity was consistently greater down there than even the most humid day in MT will be. When I did a series of gums--9 was the most I could seem to do successfully at one time--the 7-9th ones were recalcitrant in development. Here I don't see a problem with 13.
I think a couple of issues are getting confused here. As I said the other day, in my humid climate I would never think of coating a lot of papers at the same time, because I would assume that the last of them would be fogged by dark reaction by the time I got to them, although as I said, I was surprised to find that I couldn't produce a dark reaction the other day after 4 hours in 80% RH, even though when I tried this several years ago the entire gum layer was hardened in the same amount of time at a presumably similar humidity. Keith's observation also raises difficulties, as I've already noted.

However, in my own observations re humidity and sensitivity, I'm referring specifically to coatings that are printed as soon as they're dry, and I was assuming that the problems of printing in humid conditions that have been raised in these discussions have also referred to coatings that are printed in short order after being dried.