> According to Betty Hahn, the mother of modern and not so modern gum
> printers (see her volume and traveling exhibit---most recently at Eastman
> House called "Photography or Maybe Not") she recommends a 5% solution
> (achieved by weight of the salt) of potassium bichromate. For myself I
"Darkroom," by Lustrum Press (Ralph Gibson's imprint) 1973, distributed by
Light Impressions, has an article by Betty Hahn on her gum process. Here
she says she uses a 10% solution of potassium bichromate -- although she
could have changed that later. I was, however, struck by the fact that
she said she uses one part sensitizer to 3 parts gum arabic. The later
manuals (and the way I was taught) mostly said one part gum to two parts
sensitizer -- in pursuit of speed, I suppose.
The article shows her gum printing on cloth, and reproduces a couple of
her gums in green on "Rives" (presumably BFK), which look great.
This book ... to be found used here and there.... is excellent throughout.
(In my opinion the sequel, Darkroom 2, was not nearly as interesting.)
cheers,
Judy
> just use a saturated solution, warmed up to 100 F to guarantee a good load
> of the chemistry. If there are plenty of crystals at the bottom of the
> bottle, it is saturated, if not, it is not. Works just fine for gumoil and
> gum printing. You may classify this advice in the touch of cilantro, dash
> of salt style of alt proc printing. Karl