Re: humidity and gum coating
What kind of sizing did you use? I'm no gum expert, but I would think that paper sized with a hardener as opposed to gelatin alone wouldn't try to soak the pigment in. My experiences with gluteraldahide seemed to completely isolate the emulsion from the rest of the paper. Just a thought... Camden Hardy camden[at]hardyphotography[dot]net http://www.hardyphotography.net On Sat, September 2, 2006 10:12 pm, Judy Seigel wrote: > > > On Sun, 3 Sep 2006, Tom Sobota wrote: >> As to why some papers develop spots when coated wet, that's a good >> question, >> I haven't the slighest idea. Differences in surface porosity come to >> mind, >> but these papers have been double-coated with gelatin and hardened ... > > > For the sake of "experiment," I tried coating the gum emulsion on > pre-wet paper a couple of times a while back, and found some spotting, but > mostly staining. Serious staining. I theorize that even though the > surface was blotted off, the interior remained wet and that the emulsion > soaked down & settled in there -- in other words, got tangled into the > paper fibers, as it doesn't when it just sits on the gelatin-sized > surface. > > I gather the reason for coating wet in the 1st place is to get an even > coat. IME, coating with a fairly wide foam applicator (the kind with the > wood handle that has been very slightly dampened & then blotted dry) and > NOT NOT NOT hake brush, spreading swiftly and THEN smoothing with dry > hake, solves any problem with coating. > > It's important however to move across the surface quickly, meaning in wide > free strokes. Trying to "smooth" as you go (instead of later) slows you > down, and (I find) by the time you get across, it's started to get tacky & > stripe-y where one stroke passes the next. In other words, the risk of > streaks is with the initial dispersal. Once that's done, you can "buff" at > relative leisure. > > However, this works best with a relatively thin emulsion, at the very > least equal parts am di solution & gum... > > Judy >
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