Re: glyoxal yellowing now: How do you know it's hard?

Don Bryant wrote:
>

>
> It's my impression that the yellowing begins as soon as the sized paper is
> dried but may continue to yellow over time.

Thanks, Don.

A joke on me: when I read this I was holding a little pile of different
papers that, just out of curiosity, I had sized with some of the rest of
the glyoxal-gelatin mix, some rinsed and some not rinsed. I glanced at
the top paper, and saw that it was positively ivory-colored. I thought
"My gosh, he's right, it's turned ivory in what, 4 hours?" then I
realized that the top paper was Arches Aquarelle, which is a very
warm-tone paper; none of the other papers had turned ivory and in fact
the Arches was just being the color of Arches.

>
> Now my question is does the yellowing ever occur when the gelatin is
> hardened with formaldehyde or formalin?

And what IS the yellow, exactly. I mean, chemically, what is it.

kt
Received on Fri Feb 4 22:48:01 2005