Re: Stain and exposure (was: Re: Gum image has reversed

On Jan 12, 2006, at 12:37 PM, Judy Seigel wrote:

> In my experience whether or not the paper has had a gelatin size,
> as well as the bloom, percent & number of coats of that size are
> crucial and i mean CRUCIAL variables in effects like staining,
> reversal, et al of coating. Katharine, as I recall, doesn't size at
> all -- but also didn't say which paper she used -- I also forget
> (if named) the paper and size condition of the reported reversal...
>
> Ahem -- IT SEEMS TO ME that any intention to test or repeat those
> findings would need to replicate the conditions of and on the
> paper. Either that or the major *finding* would be: On such and
> such paper this did or didn't happen.
>

Ahem, yourself.... I can only assume that you haven't actually looked
at any of the pages I've shown, of observations related to this
issue (not "findings;" they are much too preliminary to be called
anything but observations) because each of the pages states clearly
that all the prints were made on Arches bright white paper, sized
with gelatin and glyoxal. I have also produced stain and tonal
inversions on glass, as has Tom Sobota (which would rather argue
against the idea that paper and sizing are crucial to stain and
inversions) but to my annoyance I can't do it today with the same
pigment mix; instead I get positive tonal images, although somewhat
pigment-stained, with the same pigment concentration that gave me
tonal inversions on glass a couple of weeks ago and heavy stain on
sized paper a couple of days ago. So I'm inclined to think that the
reversal thing is even more unpredictable than I was giving it credit
for, which was quite a lot.

Besides the fact that staining and inversions can be produced on
glass, it also seems to me I've rather ruled out the effects of
paper and sizing by showing both stain and inversion that were
eliminated by simply changing the pigment concentration. These
comparison prints were made on the same sheets of sized paper, cut
into pieces, so it couldn't be anything about the paper or the sizing
that accounts for the difference.

Let me be very clear, if I haven't been already, that the pigment
mixes that are within gum's ability to hold pigment in suspension, in
other words that don't result in stain or inversion, are not wimpy or
underpigmented mixes. For example, in the case of the partial
inversion I showed in PV19, compared to the tricolor subsequently
made with 1/3 more gum in the PV19 mix, the tricolor, while a good
strong tricolor, was magenta-biased. In other words, even though the
improved mix no longer made a stained (reversed) print, it still was
a bit too strongly pigmented for tricolor.

I'd tend to agree that when we're talking about normal pigment
loads, whether pigment stain occurs or not is often (although not
always) a function of paper and size. . But I'm not talking about
normal pigment loads here, as should have been clear from my
discussions; I'm talking about way overpigmented coatings, which in
my observations have been responsible for both stain and tonal
inversion.

Katharine
Received on Thu Jan 12 17:30:39 2006