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

Re: Gum Humidity Question

I totally concur, Kerik. It may be 50% or more humidity outdoors, even
raining, but that has nothing much to do with humidity indoors. Even in SC
where the humidity was dripping, it wouldn't be more than 60% in the house,
so Kerik, 80% is BRUTAL. My house here in the summer has averaged in the
20's to 30s and I know it is not that low outside. My hygrometer measures both inside and outside temp and
humidity, and it wasn't costly--maybe $50. I think I bought it from
Hammacher Schlemmer or Brookstone or Sharper Image or some such...I have
never really printed above 50 or 60% humidity. In SC I never let the indoors
get that high or stuff molded. The closest I came to printing in high
humidity was in MN in my little back cabin that had windows all around and I
had them open.

Down in SC I would notice spontaneous hardening of emulsion from the first
to the last gum print when I was doing 9 at a time; here I can go a very
long time (did 13 at once this weekend) and no noticeable effect on prints
at the 33% humidity level. So these hygrometers are worth every penny I
spent to really get a handle on actual "working strength" humidity. I
actually have 2 because I consolidated two darkrooms--MN and SC--into one,
so I check my gauges against each other.

We get several 100% humidity days where I live, but the humidity in my
area is more like 50 to 60% in those conditions. The 80% and 80 degrees we
had on Sunday were measured IN the work area. I've read that these
inexpensive hydrometers read a bit on the low side, so it may have been a
little higher than that.
This is all good information, though. Weather it's speed or an effect on
sizing or something else, something is definitely going on here.