Re: report on glyoxal yellowing

Carmen and Candace,
     I apologize for replying to two emails at once, but:
Carmen, the yellowing does not occur right away, but after, let's say,
several weeks or more, or even less. Clay Harmon noticed his in a week.

Candace, I went back over the archives to see what other papers yellowed,
and unfortunately I couldn't see any paper names mentioned. I know Clay and
Kerik both experienced yellowing. So did Kees Brandenburg.

There is disagreement whether, once the yellowing occurs, it is removable
with a soak. Judy says yes. Kerik says no. I think my answer is no, but
I'll soak my measely little strips and tell you.

I attach a message at the end from Kees about this from a couple years ago.
Otherwise,
you can search for "glyoxal and yellowing" in the list archives from about
1999 onwards.

For those of you long term listies (I've only been on since 99), who
instituted the use of glyoxal for hardening in alt process? Luis Nadeau
says this below. Dick Sullivan, do you know? I've cut and pasted this.

" Luis Nadeau (nadeaul@nbnet.nb.ca)
Tue, 19 Jan 1999 16:25:56 -0400

I'm curious, does anyone know the long term effects of glyoxal on paper?

It's been used for decades in the photographic industry. I first read about
it when studying Pierre Glafkidès' _Chimie et physique photographique_ in
1976. The previous edition may have had it as well. The effect should be
the same as formaldehyde.

Luis Nadeau
Fredericton, NB, Canada "

And "Kees said, "These are my observations with glyoxal and yellowing:

I coat my paper for gum in a 3 % gelatin solution by immersion in a tray.
After drying (at least one night) I soak the paper in 1 liter of
water containing 25 ml of a 40% glyoxal solution with some borax
added. In fact I am copying exactly as I was doing with formalin.

After 2-3 minutes in the bath I put the sheets in a tray with running
water and leave them in for some minutes.

After drying there is no apparent yellowing. But....when these papers
are kept (in the dark) for some weeks an significant yellowing is
visible alover but most apparent at the edge where the gelatin is a
litlle thicker.

The yellowing was more severe when I started using glyoxal. At that
time I did not rinse the paper afterwards as I do now.

I think there is indeed a relation between concentration and yellowing.

glutaraldehyde

Apart from this I looked at glutaraldehyde too and found in the
archives that MACO hardener (LP-Geladur and MACO LPE 510 hardening
additive for Black Magic emulsion) contains glutaraldehyde too.

As I have a bottle of LP-Geladur here,I asked MACO for the exact
proportions and they kindly did send me a recent (Feb.9 2004) safety
sheet. It says:

disodium disulphite 5-10 %
glutaraldehyde 2-5 %
acetic acid 0,5-2 %

Apart from these figures being not too exact (but good enough for
safetysheets I presume) one can see indeed that the glutaraldehyde
concentration is rather low. Especially when knowing that the
solution is a concentrate to be diluted before adding (to the liquid
emulsion). For hardening their photogelatin they advise a working
solution of 5 ml concentrate on a total of 100 ml water. From this
dilution one should add 20-50 ml per liter gelatin solution. What I would
like to know (I will try if it works myself too of
course) what the acid and the bisulphe are doing in the hardening
process. Disulphite is often advised to neutralise glutaraldehyde
before disposal. And I was thinking that an acid environment
prevented an effective hardening by aldehydes." Kees Brandenburg

----- Original Message -----
From: "Carmen Lizardo" <carmenlizardo@yahoo.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Saturday, November 13, 2004 2:59 PM
Subject: Re: report on glyoxal yellowing

> Dear List,
> Yesterday sized Fabriano Artistico and LanaAquarelle
> hot press paper, using knox gelating and hardened
> using 15ml of Glyoxal, 1/2 tsp of baking soda per
> liter of tap water. I found no yellow stains.
>
> Carmen
>
>
>
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Received on Mon Nov 15 07:05:08 2004