Re: APIS, hydroquinone hardening

From: "Christina Z. Anderson" <zphoto@montana.net>
Subject: Re: APIS, hydroquinone hardening
Date: Wed, 13 Jul 2005 17:57:50 -0500

> I personally love glutaraldehyde if I can ever spell it correctly,
> and use that in my practice, and I agree with Ryuji's comments,
> below.

Isn't it in your spell checker dictionary along with Kodachrome?

> [...] my idea would be to size the paper in a tray of the
> di/gelatin, and then pass it thru a bath of the hydroquinone (Paul
> had added a pinch of hydroquinone to the gelatin/di mix and voila,
> instant hard, which is why I thought to try the bath of
> hydroquinone).

Although I agree that hydroquinone should be supplied after
dichromated gelatin is coated to go around rapid reaction between
them, I don't think immersion is a good idea. Immersed paper would
contain excess hydroquinone, and unless you remove this, it can cause
elevated fog with dichromated gum process (and it can completely fog
silver gelatin process). You could reverse this and coat hydroquinone
and bathe in dichromate, but that would produce a lot of waste
chemical containing chromium (bad for environment).

If you take this approach, my preferred strategy would be to find a
compatible reducing agent for dichromate, but one that reacts only
very slowly. This way, you can mix gelatin, water, dichromate and
reducing agent in one coating solution and coat. Sized paper will be
hardened by the time it is fully dried.

My conclusion: glutaraldehyde.
Received on Wed Jul 13 23:41:04 2005