Re: Hardening gum

From: Katharine Thayer <kthayer@pacifier.com>
Subject: Re: Hardening gum
Date: Thu, 18 Mar 2004 17:14:34 +0000

> I thought my correspondent was arguing that I should assume that gum and
> gelatin are chemically equivalent,

I never said that. I said that binding of chrome (III) and carboxyl
group is the same in gum or gelatin. We never talked about similarity
or difference between gum and gelatin in more broader contexts.

> What's interesting, given Ryujii's statement that gelatin and gum should
> behave similarly with regard to chrome alum, but not necessarily with
> regard to the aldehydes, is that after many tests involving increasing
> concentrations of chrome alum I have yet to successfully harden gum with
> it, but just a drop of glyoxal hardened the gum very nicely.

That's a little surprise to me.

> The disappointing thing is that any hardening method (including gum
> bichromate, now that I think of it) seems to destroy the lovely melting
> sheen of the dried soluble gum, and it may be that only when it's
> soluble will it have that lovely sheen, in which case this whole thing
> has been a wild goose chase.

Did you test with diluted glyoxal?

Can you test the same idea with gelatin or PVA?
If it works, PVA is probably much easier to use.

Well, if you really love that look, it should be worthwhile looking
around for suitable material for your project...

--
Ryuji Suzuki
"All the truth in the world adds up to one big lie." (Bob Dylan 2000)