U of S | Mailing List Archive | alt-photo-process-l | Re: Gum and Photogravure, was: varnishes

Re: Gum and Photogravure, was: varnishes

16 Kasım 2008, Pazar, 8:50 pm tarihinde, Katharine Thayer yazmış:
> ...
> A gum printing, on the other hand, is not made of pigment permanently
> coloring the paper fibers, but of hardened crosslinked gum arabic, in
> which pigment is suspended like a beetle in amber. The hardened gum
> is attached to paper fibers to hold it to the paper,  but the pigment
> is suspended within the hardened gum rather than permanently staining
> the paper fibers as in watercolor paintings, so the image is made of
> a different entity in each case.  I have no information to bring to
> bear on the question of relative permanence of the two things, and if
> anyone else does, I'd be interested to hear it, but I'm not
> comfortable saying that the permanence of one should be considered as
> a predictor of the permanence of the other, since they differ in such
> important respects.
> Katharine

Perhaps, but in that case what is the fact that makes gum prints as stable
as carbon prints (you said that earlier in this thread) whereas they
differ so much in binder? (One gelatin, the other gum arabic.)

On the other hand you used a nice description "...like a beetle in
amber...", since we know that they're beetles fossilized in amber as old
as millions of years, maybe there isn't much difference between amber and
gum (both being sap of their particular trees) so we can pretty be
confident that gum prints could be quite stable. No?

Regards and thanks for the contribution,