Re: Gum Humidity Question
Did you change the exposure to compensate for the change in humidity? Candace Spearman ----- Original Message ----- From: "Katharine Thayer" <kthayer@pacifier.com> To: <alt-photo-process-l@usask.ca> Sent: Tuesday, September 26, 2006 5:24 PM Subject: Re: Gum Humidity Question > P.S. I will say, however, just as a general anecdotal observation, > that I haven't seen noticeable differences in contrast between prints > I've made at 100% humidity (in the air, not in the gum coating) and > those I've made at 60%. > Katharine > > > > > On Sep 26, 2006, at 2:31 PM, ericawd wrote: > > > According to Christina Z. Anderson and Kosar: > > > > 7. Humidity: The presence of a certain amount of moisture in a > > coated and > > dried layer is necessary for the hardening reaction. When dry, the > > moisture > > remaining varies with relative humidity. Completely dehydrated > > or fully > > swollen coatings do not show any light sensitivity at all, but in > > between > > the sensitivity is high when the humidity is high. Sensitivity > > doubles with > > increase of 30% humidity. > > > > In my experience, I have found the above to be true. My question > > is, in the experience of the gum printers, what effect might > > humidity have on contrast? Lower humidity equals higher contrast > > or vice versa? All other things being as equal as they can be with > > gum. > > > > Candace Spearman > > > > > > > > > > > > > >
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