RE: Gelatin hardening question - Now glyoxal again

Since you've sent my question down a different track, let me ask a couple of
questions about glyoxal. Does it harden better/faster than chrome alum?
Can it be added directly to the gelatin mix, or does the hardening have to
be done as a separate step?

-----Original Message-----
From: Clay [mailto:wcharmon@wt.net]
Sent: Wednesday, July 14, 2004 4:12 PM
To: alt-photo-process-l@sask.usask.ca
Subject: Re: Gelatin hardening question - Now glyoxal again

Perfect lead-in to a recent observation I have made. Everyone on the list
remembers the mysterious glyoxal-yellowing-the-sizing that some of us get if
we don't start applying gum layers promptly. I had sized about 7 prints just
prior to vacation, and started (and finished) all but one. Since I wasn't
going to get to this last print, I decided to try just washing the print for
5 minutes and then letting it dry. Two weeks later, I returned home, and
there was no yellowing!

Now I know from personal experience that had I left it on the rack without
rinsing it, it would have definitely yellowed. So Judy's (and others if I
remember) surmise that the glyoxal needs to be rinsed out of the paper after
it has done its salubrious job of hardening the gelatin appears to be on the
money. Now, this is only one occurence, on one kind of paper, but it
certainly seems consistent with my experience that getting down to the
business of doing gum layers will prevent the sizing from yellowing. FWIW

Clay

----- Original Message -----
From: "Keith Gerling" <Keith@gumphoto.com>
To: <alt-photo-process-l@skyway.usask.ca>
Sent: Thursday, July 15, 2004 3:52 AM
Subject: Gelatin hardening question

> I've been having some sizing problems lately. Problems I never have in
> months that are cold and dry. I harden gelatin with chrome alum and give
it
> a day to harden. Searching through the archives, I found a post where
> Philippe Monnoyer mentions that chrome alum takes up to a month to
> completely harden. Can someone elaborate on this? The degree of
hardening
> per unit of time is obviouslynot linear. What degree of hardening takes
> place in 24 hours? How about in a week? Would glyoxal harden faster?
> Lastly, is higher heat and humidity known to have a factor in the
hardening
> process?
>
> Thanks.
>
> Keioth
>
>
>
Received on Wed Jul 14 15:52:22 2004