> >And the good news is -- samples of two of the 3 papers I did stain
> >test on (using a very stainish ultramarine blue)
>
> something is missing here. You put the blue pigment in the gelatin?
No. I had paper sized with gelatine that had been hardened, some in
glyoxal, some in formaldehyde. But that was NOT the end purpose of the
project -- a gum print was (maybe one of these days I'll actually make
another one). So, I mixed Rowney ultramarine watercolor with gum arabic
and ammonium dichromate, and coated, dried, exposed and developed the
paper just as for a gum print, to see how the size-hardener combination
"worked."
I used this particular color because it's difficult, has a tendency to
stain, which is what I was testing for. Some colors hardly stain no
matter what you coat them on.
>
> >developed whiter with
> >the glyoxal. Yes, whiter than white!! A third paper was about the same.(The
>
> There are excellent pigment printing books on the market that explain why
> blue pigments can make some materials appear whiter than white;-) The same
> can be said of optical brighteners in general.
Actually, a couple of samples looked yellow, since I used Rives
Heavyweight in its yellow version for some of the tests. But the fact that
the glyoxal paper came out totally clear & clean in highlights (under
21-step wedge), much clearer than the formaldehyde paper, and did this not
in just one test which could have been a fluke (very common fish in gum
printing) was, I thought, remarkable.
Now we must ask.......what took us so long? Unless something else pops up
not yet apparent, it would seem there's no downside to the switch.....
Judy