Re: archivalness of gum
Thanks, Ryuji. I actually bought a bottle of formalin to do some tests with, and then for a moment in this discussion thought it might even be a good idea to use it :)[...] I wonder if use of formaldehyde for hardening gelatin gives the benefit of preserving it from bugs...No. Ryuji Suzuki
Judy, you are absolutely right about "carbon carbon" and this was questioned long ago (1800's), why call something (either the gum version or the gelatin version) carbon when carbon was only one of MANY possible inclusions to use? HAHAHAHA gum got smart, carbon printing didn't :). It ditched the name "direct carbon" centuries ago.
I am writing the gum book in this way, which provides me with a side benefit of a wonderful way to see practice morph through time: I typed up all notes (200 sources plus 60,000 pages of the BJP). Then I cut and paste **in order of appearance** sentences into different topics. One topic, for instance, is pigment (separate from "pigments not to use" (that "cause problems") separate from "pigment mixes"). Not only do I see what morphs through time, but also where myths began.
It was a very short time that they went from carbon to colors, and there were many recommended colors once they got "past" just using carbon black. Of the slew of recommended colors were Indian Yellow, Gamboge, the "Lakes", alizarin crimson, rose madder, etc.--all these colors that we know now fade. Then they got wise and began not recommending these colors, recommending more permanent ones, of which the earths or oxides seem rarely in question (Kuhn loved that iron oxide red). (Still no question of archivalness of gum, though...) Anilines were frequently verboten for staining and fading reasons, and this is an area I need to research more because we do use a lot of those nowadays so something in the making of analines might have changed....
I also found that during war years, there were certain fillers in tube pigments that weren't allowable (platinum availability disappeared during war years, too). Egg, for instance. The tube pigment fillers were replaced with other substances, which created issues with gum. So some of the "pigments don't work" myths may have not been myths at that time due to the tube paint ingredients. There would be nothing wrong with gum arabic in paints nor with albumin(ate?) because both are colloids, but who knows what else might have been used. It's little points like these that make it such a fascinating read.
BTW the first "this pigment doesn't work" was 1894.
And, Judy, as an aside, I have a nice little chapter on the dreaded stain test, tracing its origins, who brought it from Germany to England and then to America. Word for word..culprit for culprit. I'm dedicating that chapter to you :) There was the distinct feel that the Germans were more scientific about gum and hence "modern" or "better". But we postmodernists know better than to be scientific about gum, heheheheheh.
My morning epistle is finished...I'm finding the alt list such a wonderful diversion from the job at hand.