spots and dots and other gum stuff
What a week, Researching at the Eastman House Library is like being in a candy store. They have all the back journals, complete sets. I thought 2 weeks would be too much and now I know it won't be enough. I've been having a heyday in back issues of Photo Beacon and Camera magazines. Joe Struble showed me some gum prints in the archives, and I will see more next tuesday. I saw a wonderful box of gums from Frederick Ives, who printed tricolor over cyanotype. The interesting thing about his work is he believed that in order to get a full tonal range in gum, you had to print with halftone screens. He developed his own halftone stuff, and if you take a loupe to his gum prints all of them are printed with a fine screen. They are quite lovely. I think I'll get home and try different sizes of halftones some more. Mark Nelson, you asked about humidity a while back affecting gum. I came across a fun and thought-provoking quote that might sum it up for you: from the Photo Beacon 1904, a Mr. Warburg: He hastened printing by placing damp paper behind the sensitive paper! "For it is not true that it is necessary for gum bichromate paper to be quite dry in order to be very sensitive; and it is also untrue that the moist coating in insensitive. The paper is most sensitive shortly after coating, when the gum bichromate film is no longer sticky, but the paper is still damp. Further drying diminishes the sensitiveness, but dampening the paper again increases it. This variation in the sensibility is so considerable and noticeable that it is curious it should not have been recognized and used long ago." Warburg says he printed for 6 or 8 years with an actinometer and measured all this stuff. I met list member Gawain Weaver today--his name is not GahWAIN but GOWuhn (does that make sense?) Always a great benefit to put names to faces. He took me on a tour of the conservation section of the Eastman House--pretty amazing. I also met, inadvertently, Mark Osterman who happened to be in the library researching at the same time. We talked for a while before I even knew his name! Funny who you run into. I finally am sure that a "2 in 5" gum solution is really 2 parts gum PLUS 5 parts water--one author even clarified this. And Whipple says this: 30g in 100cc is referred to by some as a 30% solution but in actuality it is a 25.3% by volume because it only makes up 119cc; it weighs 130g so it can even be called a 23.1%solution by weight. He points out that using percentage solutions can be unclear, in the gum field anyway. I have found that the variation in gum strength is pretty major throughout practitioners. Judy, the dreaded titration gum stain test that Koesters originated is repeated in the Photo Beacon of 1906. So it went from Germany to England to America....in this day and age of instant info I am surprised at how slow news of trends flowed back in the day. Enough for now! Chris CZAphotography.com
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