[alt-photo] Re: Gum Printing: Looking for some wisdom
workshops at polychrome.nl
Thu Mar 7 18:56:07 GMT 2013
As we are talking about gum, let's not forget this variable. What gum arabic do you use? Premixed or self mixed, and at what concentration and baumé? I'm using a 14-14,5 baumé self mixed gum. This is about 26-26,5%
Looking at your exposure times for cyano and van dyke, compared to mine (6 and 4min) I would say that you would end up somewhere around 10 minutes with your bank of UV and normal gum sensitivity. I find your pigment concentration rather low. With 'normal' strenght gum I am using 1 gram per 20ml gum for winsor blue and lamp black on gelitin/glut sized paper and never see any stain.
With dichromate I'm a 'replenisher'. When the bottle seems to empty with a coming workshop or project, I make some new and fill the bottle up. From time to time it stands for several weeks or more.
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