From: Kate Mahoney (kateb@paradise.net.nz)
Date: 09/07/03-03:42:44 PM Z
Gee Etienne! that sounds really complex! But I suppose it's worth it!
----- Original Message -----
From: "Etienne Garbaux" <photographeur@softhome.net>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Monday, September 08, 2003 4:22 AM
Subject: RE: coating method
> David and Ryuji wrote:
>
> >> I am aware that gelatin is only one of several effective subs [...]
> >
> > But I don't know what else would work well on glass.
>
> Sodium silicate, isinglass, and albumen are all successful subs for
gelatin
> on glass. A number of modern synthetics are probably "better," but all
> three of these will bond gelatin to glass strongly enough that if you tear
> the gelatin off it pits the glass.
>
> Some people put the emulsion down directly on the sub, others use a layer
> of chrome-hardened gelatin in between. I only do that when I'm dyeing the
> hardened layer to act as an anti-halation layer.
>
> If you get the glass properly clean (see below), chrome-hardened gelatin
is
> an acceptable sub, or you can even get by without a sub if you keep
> processing temperatures and developer alkalinity moderate.
>
> The hardest part is getting the glass CLEAN. You need to SCRUB the plates
> in a strong, HOT soap solution followed by a strong, HOT acid bath
followed
> by a strong, HOT alkali bath followed by a strong solvent bath (nitric
> diluted 1:1, concentrated sodium hydroxide, and acetone, in my case) with
> distilled water washes in between and after, then a final dip in acetone
to
> make them dry quickly. The acetone must be reagent grade, not hardware
> store, which contains traces of oil and other junk and will undo all of
> your hard work. If you have benzene [note to our Brit colleagues: NOT
> benzine], and are willing to work with it, that's even better. Yes, the
> in-between washes need to be distilled water, not tap water. Once you've
> gotten the glass clean, you'd be surprised how well gelatin adheres with
no
> sub.
>
> Best regards,
>
> etienne
>
>
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