Re: Hardening gelatin

Ignore my previous post, sorry. I thought about this again and decided
that there are too many variables that can't be standardized across the
comparison to draw any useful conclusions, even if I could work out the
details of how to compare hardening in the two materials. And the truth
is, while I'm very interested in hardening gum, since it has direct
implications for a project I'm working on, I'm not in the least
interested in hardening gelatin and not willing to spend any time on
thinking about gelatin hardening. As you were,
kt

Katharine Thayer wrote:
>
> While thinking about my experiment in hardening gum, I got to wondering
> how people who harden gelatin for sizing actually know that hardening
> has taken place.
>
> What I'm hardening is watercolor paint with gum added to it, the same
> gum/pigment mix that I use for gum printing. Dried unhardened gum is
> very soluble in water; that's one of the basic principles that underly
> the gum process, after all, and the added color makes it very easy to
> tell whether the gum has been hardened: just drop a drop of water onto
> the dried gum/paint and blot. If I get a round white spot where the drop
> of water dissolved the gum back to white paper, I can be sure that
> hardening didn't take place.
>
> But when you're hardening gelatin, how do you know? Since, like Judy,
> I've long questioned the wisdom of assuming that the chemistry of gum
> and the chemistry of gelatin are interchangeable, it occurred to me that
> this might be one place where I could compare the two in some kind of
> quasi-systematic way, since I have these hardening agents that are
> usually used for gelatin, that I'm using to harden gum with. If gelatin
> and gum behave similarly in this case, then I would have to consider
> softening my resistance to the idea that gum chemistry = gelatin
> chemistry.
>
> But right away I'm up against this question: if I do this comparison,
> how will I know that the gelatin is hardened? In my experience dried
> gelatin isn't as hypersoluble in water as gum is; I doubt that dropping
> a drop of cold water onto unhardened dried gelatin would dissolve it
> instantly in the same way that a drop of water dissolves unhardened
> dried gum; it would have to be hot water for that to happen, yes? If the
> hardening can't even be judged under the same conditions, how could it
> be argued that the two things are functionally the same?
> kt
Received on Thu Mar 18 14:37:45 2004