Re: glyoxal yellowing

Chris,
As you can see there was some yellowing measured in my rinsed paper too
(Y 0.08, maybe not significant) and a yellowing at the borders. I never
noticed any grittines with glyoxal (15 or 25 ml per liter). I even went
back to formalin for that for some time. But, that really awfull!
Couldn't imagine I used that for many years.

As I am doing gum workshops on a regular base I have allways a lot of
sized paper around. In the end I find the very slight (rinsed glyoxal)
yellowing acceptable but still have to see if the finished prints
continue to yellow and if there is a relation between exposure to light
and yellowing. My samples were kept in the dark.

About the Maco Geladur glutaraldehyde: these percentages are frome the
Maco safety sheet.

Next weeks I will be sizing again and I will try to find some Fabriano
Artistico EW here. I do have some old Fabriano Uno and Rives BFK and
will make samples of these too. And do some test printing on the
glut-papers (Fabriano Uno hot pressed).

Kees

Christina Z. Anderson wrote:

> Kees,
> Great results and diligence! (you still deserve it even with a typo.)
>
> Is there a chance you could obtain a sheet of Fabriano Artistico EW
> paper and test your process on that, too? I did the afterbath and
> rinse process with the lower dilution of glyoxal (15ml) and still got
> yellowing.
>
> If you do not have access to that paper and aren't too far away, I
> would gladly send you a sheet.
>
> Don, I always get grittiness with glyoxal and never use baking soda
> (and the next time you come I'm going to accidentally sprinkle baking
> soda on your morning strawberries).
>
> Kees, the Maco hardener---very interesting! Is the percentage of glut
> in it really 2.5-5%? If so, then 50 ml of this is a lot more than my
> 6 ml. per liter of gelatin. BUT, if this is truly a 2.5-5% glut,
> then a consumer would be able to buy glut over the counter in small
> quantities and that is a great thing! Also, any dire warnings on the
> back of the bottle? Maybe I'll just have to buy some...this would
> totally solve my problem of how to harden gum in a classroom situation.
> Chris
>
> From: "Kees Brandenburg" <ctb@zeelandnet.nl>
>
>> sample 1: M 0.06, C 0.06, Y 0.07 (unsized, unhardened)
>> sample 2: M 0.06, C 0.06, Y 0.07 (sized, unhardened)
>> sample 3: M 0.06, C 0.06, Y 0.07 (sized, soaked for 3 minutes in 1
>> liter water with 15 ml formalin(37%), dried )
>> sample 4: M 0.06, C 0.06, Y 0.08 (sized, soaked for 3 minutes in 1
>> liter water with 15 ml glyoxal (40%), rinsed for 5 minutes in running
>> water, dried )
>> sample 5: M 0.06, C 0.06, Y 0.12 (sized, soaked for 3 minutes in 1
>> liter water with 15 ml glyoxal (40%), dried )
>> sample 6: M 0.06, C 0.06, Y 0.07 (sized, soaked for 3 minutes in 1
>> liter water with 50 ml Maco Geladur (this is a 2.5 - 5%
>> glutaraldehyde solution), dried )
>> Conclusion stays unchanged: unrinsed glyoxal hardening yellows paper,
>> rinsed glyoxal hardening gives no visible yellowing on the surface
>> but slicht yellowing at the edges. All other hardening does not
>> yellow paper.
>> kees
>
>
>
Received on Thu Feb 3 09:42:14 2005