Re: Gloy is NOT PVA

On Mar 27, 2006, at 2:02 AM, davidhatton@totalise.co.uk wrote:

> Hi Katherine,
>
> As confirmed by Ryuji, PVA(H) wasn't discovered until 1924. This
> alone is sufficient to exclude it (PVA) from the constituents of
> Gloy which
> appears in literature prior to 1920. One of the articles I read
> stated that Gloy was a mixture of Dextrin and Magnesium Chloride
> but doesn't
> give any details. A more modern recipe is more precise being
>
> Yellow dextrin (95% soluble) 65.7 pbw
> Water 32.9
> Tributyl phosphate 0.2
> Heat to 88°C for 30 min, cool to 60°C, and add Corn syrup 1:1
>
> It may seem that I'm being pedantic about this issue but I'm
> concerned that the product referred to in Alt Photo literature may
> not be the
> product available now with the chance that the methods described in
> those tomes may not work as described.

David,
All my knowledge of the use of Gloy for gum printing comes from
recent history, not from the old literature; I wasn't even aware that
Gloy was mentioned in ancient tomes. By all accounts the modern PVA
Gloy (I thought it had been discontinued 2-3 years ago, am I wrong
about that?) prints fine, just like gum; in fact someone sent me a
little sample of it three or four years ago and I printed it myself,
so I've seen this with my own eyes, as well as having no reason to
doubt the Gloy users of the world.

> I also want (if I need to)
> produce a colloid which works, using readily available every day
> products in my own kitchen :)

Well, that's a different matter altogether, and more power to you.
But you could print with gelatin if you want something that's
available in your kitchen.

Katharine
Received on Mon Mar 27 09:21:35 2006