Re: Gum and Photogravure, was: varnishes
In regard to watercolor paintings... not true that the paint stains the paper and is permanent if the gum is washed out. Many watercolor pigments remain suspended in the gum and sit on the surface of the paper. Only some of the pigments actually stain the paper, and even in those cases if you wash the paint from the surface, the color lightens considerably due to the removal of the top layer of gum/pigment. Having been primarily a watercolor painter for quite a few years, quite a few years ago... I have a lot of experience that includes removal of color from areas both large and small while developing a painting. In fact, terms used by watercolor painters include "staining" and "non-staining" colors.
As to the discussion about the permanence of printmaking ink on paper... that is something I have always wondered about myself. Why is is ok to use oil based ink on paper for an etching, but not when "painting"? Rembrandt's etchings are what... over 300 years old? It must have to do with the smaller percentage of oil in ink when compared to oil "paint".
On Sun, Nov 16, 2008 at 1:50 PM, Katharine Thayer <firstname.lastname@example.org> wrote:
" In the case of watercolor paintings, the image is made of what we in gum printing would call "pigment stain;" it's comprised of pigment which has penetrated the fibers of the paper and colored (stained) them permanently. The gum arabic is only there to serve as a vehicle for the pigment, and its presence in the painting is essentially irrelevant; at any rate after diluting the paint from the tube with water in the typical watercolor painting, there's very little gum arabic in the painting. You could soak most traditional watercolor paintings in water and dissolve the remaining gum arabic without affecting the painting in any material way."
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