Re: Glyoxal?

Yves,
Sorry, I must have missed this post.

There are a few ways to harden--formaldehyde, glutaraldehyde, alum, glyoxal.
I suggest doing an archive search for those 4 items. You will find lots of
discussions and formulas for these in the last several years, and some good
formulas. Some use alum quite regularly, formalin is used a lot, the
newcomer on the block is glut with not enough data to give you a yay or nay.
Just that I use it always, and I am teaching it this semester to my
students, too, and I know of at least four others that are having great
success with it as a hardener. that is 6ml of 2.5% added to 1 liter of 3%
gelatin.

I think all of the hardeners have toxicity and cautions...use extreme
chemical practice with these because since they harden colloids they harden
eyeballs. When I teach sizing this semester I will add the glut to the mix
myself and not let unwary students fool around with it, to be safe. You
know, though, with how people treat superglue like it's no big deal....makes
you wonder.

Those that don't get yellowing with glyoxal seem to usually harden, and then
rinse after hardening right away or something of that nature. Or use the
paper quickly.

Personally, if I wasn't using glut I would go to formalin before glyoxal.
It's worked for centuries--well, 1 1/2 centuries.

chris

----- Original Message -----
From: "Yves Gauvreau" <gauvreau-yves@sympatico.ca>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Thursday, January 12, 2006 6:46 PM
Subject: Re: Glyoxal?

> Thanks Christina,
>
> are there other ways (other stuff) to harden the gelatine without causing
> a
> change in color and I assume doing all of this we must keep a neutral ph
> or
> whatever is best for archival.
>
> Regards
> Yves
>
> ----- Original Message -----
> From: "Christina Z. Anderson" <zphoto@montana.net>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Thursday, January 12, 2006 4:11 PM
> Subject: Re: Glyoxal?
>
>
>> but I don't bother to rinse
>> > as a step in the sizing process because the development bath in the
>> > gum
>> > process restores the paper to the original pristine white. So I don't
> see
>> > any necessity for a separate rinse. But you'll need to see if that
> works
>> > with your paper, or not.
>> > Katharine
>>
>> Yves,
>> Sorry to disagree here but there are a number of us on the list that
> cannot
>> get that stain out no matter how much we soak it, breathe on it, sit on
> it,
>> look at it. You can do what you want, but don't say we didn't warn you
>> :)
>> If I wanted a dull ivory paper to print on, I would have bought it that
> way
>> to begin with. It is unacceptable to me, but you may be one of the
> blessed
>> ones that don't get glyoxal yellowing. Pretty soon on my website I will
>> have an image of glyoxal yellowing to show you what I mean. However, my
>> guess is it is paper dependent, and perhaps related to my paper choice
>> coupled with my water supply. The point being, for some of us the yellow
>> does not disappear once it is there.
>> Chris
>>
>
>
Received on Fri Jan 13 18:58:26 2006