Re: APIS, hydroquinone hardening

From: Katharine Thayer ^lt;[email protected]>
Date: 07/13/05-09:14:12 AM Z
Message-id: <>

Katharine Thayer wrote:
> I agree with Ryuji here; I guess I don't get what the point would be to
> doing it this way rather than just using one of the common hardeners for
> the gelatin.

And besides, I'm a bit skeptical about a rubberlike surface working well
for gum; I've tried printing on surfaces that have a rubbery quality
(like paper coated with waterproof ink) and found that gum doesn't
adhere well to such surfaces. But will be happy to be pleasantly
surprised by data, as always.

> Ryuji Suzuki wrote:
> >
> > From: Jack Brubaker <>
> > Subject: Re: APIS, hydroquinone hardening
> > Date: Wed, 13 Jul 2005 14:58:35 -0500
> >
> > > As a fellow gum printer who doesn't feel I have found the Holy Grail of
> > > sizing options I to was excited about this idea. Paul found that a gelatin
> > > coating that contained a small amount of hydroquinone could be hardened by
> > > the addition of a small amount of dichromate.
> >
> > This can work, but the net effect should be similar to addition of
> > chrome alum. Presence of oxidized hydroquinone in absence of sulfite
> > may also help to form a different kind of crosslinking. But personally
> > I don't see why one might want to use more than one step of work for
> > the hardening process when one is enough. Addition of a very small
> > amount of glutaraldehyde immediately before coating works as good as
> > anything else I tried and it is by far the easiest hardening process I
> > know of.
> >
> > > The dichromate could be either brushed on and then washed off once
> > > the reaction had occurred or perhaps the usual gum coating could be
> > > brushed on and the sizing under it would be "set" by the dichromate
> > > in that first layer of gum.
> >
> > If you do the latter, I would expect the "fog" level to rise.
Received on Wed Jul 13 16:09:57 2005

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