Re: outdoor gum demo
I have had success with storing prepared sensitive gum paper for days interleaved in a sketchbook in the fridge. Take a tiny "Dorm fridge" with you to keep the emulsion cold. Jack On Wed, Apr 15, 2009 at 7:09 PM, Katharine Thayer <kthayer@pacifier.com> wrote: > Hi Laura, > This sounds like fun, and it also sounds like you have the right attitude to > roll with whatever punches the unusual situation throws you and just enjoy > the experience. > > First, the dark reaction is largely a function of humidity; if the air is > quite humid (like 70% or more) I'd be leery of coating the paper even an > hour ahead of time; if it's really dry (like 20-30% or less) you might be > able to get away with coating the night before, but I think I'd want to do a > test ahead of time, in similar conditions, to be sure. > > Then, ambient light during coating. During the five years I lived at the > beach, I coated my paper next to a solid wall of glass 12 feet high, and > never got fogging from the ambient light. The windows faced north and the > house was surrounded with pine trees, so there was no direct sunlight, > except that during part of the summer, just before sunset a stray sunbeam > could sometimes find its way through the pine trees and through a little > window on the west side of the studio, and expose the paper as I was coating > it, in the shape of the window frame. You definitely don't want sunlight > shining on the coating, even in the very late afternoon. > > I always dried the coating immediately (with a hair dryer) and exposed > immediately; I wouldn't recommend keeping coated paper around in reflected > daylight for very long at all. One time when I noticed a fingerprint on the > negative just as I was putting it on the coated and dried paper, I went off > to the darkroom to find the negative cleaner stuff, and when I came back a > few minutes later, the ambient light coming in through the glass had exposed > the image, with the negative just sitting lightly on top of the paper. I'm > not sure how Keith manages to dry his coated paper outside without fogging > it, but then Keith is a wizard, and also maybe it has something to do with > dichromate; I use saturated ammonium dichromate which would fog faster than > a less concentrated dichromate. So that's another thing to consider. Since > the sun exposes so fast, you can easily use a less concentrated dichromate > and still get fast exposures in the sunshine, and have less risk of the > coated paper fogging while waiting. My exposures in the sun for gum are > less than a minute with 27% dichromate. > > Forget the yellow tent. Haven't we just finished a discussion where we > agreed (I certainly thought so) that the idea that the visible color of a > thing is related to the UV-blocking capability is, well, to quote someone > else's phrase, "a nonsense" ? That goes for the pigments used to dye > material for a tent as well as for the inks in an inkjet printer. A tent > might be useful if you don't have shade where you're going to be, but I > wouldn't worry much about the color of it. > > If it were my project, and if your climate is quite dry, I'd coat and dry > the papers at home the night before, then put them in a big black envelope, > like the black plastic envelope that came with a package of big photopaper, > or even a garbage bag or something, when you carry them to the event, then > keep the bag out of direct sunlight so the coated papers don't get hot. > > If your climate is damp, (sorry, I'm quite ignorant of what it's like in > Iceland in May) then you'll need to worry about the dark reaction, which > means you'll need to consider a way to coat and dry fairly close to time of > exposure. So the climate will have a lot to do with the decisions you make. > > Hope any of that is useful, good luck! > Katharine > > > > > > > > On Apr 15, 2009, at 1:26 PM, Laura V wrote: > >> This is all very interesting...I've never "tested" the amount of ambient >> light I can get away with, since the exposure unit I use is in a dark room, >> I always coat in there, under safe light since I assumed using flourescents >> would be bad. >> >> Loris, is the idea of the yellow tent to create a safe light situation? >> >> Keith, could the fact that the coated print you found was already exposed >> make a difference to one that was just coated and not exposed? >> >> At any rate, I think I need some sort of tent to create shade, and also >> because the weather is unpredictable, it could even rain (and I guess that >> will make exposure difficult!) And Loris, I'm totally fine with looking >> awkward/ridiculous...it happens often :) >> >> Laura >> >> > >
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