From: Christina Z. Anderson (zphoto@montana.net)
Date: 03/18/03-08:49:12 AM Z
Hi Dave,
Yeah, I find that interesting, too. So what that tells me is here in
MT where it is so dry, my results may be way different on all accounts than
results from...Jamaica. But they'd probably compare to yours.
So, I'll preface the comments below with saying they're from MT so
caveat emptor:
Yesterday I coated a piece of paper and immediately exposed it wet, and
it is as dark as the paper I exposed dry, btw. No, maybe a tad lighter, but
I could've been off seconds. Certainly not scientific. Only interesting,
and supports the two sources I read that say the solution is sensitive when
wet. I suppose everyone already knew that but me :)
Here's another interesting variable: Daniel Smith says in their new
catalog that for some reason the gum they are getting now is more acidic
than in the past. That will also affect the process.
The D.S. catalog mentions another interesting point: that gum arabic
is used in watercolor to achieve granulation of pigments! How about that?
Maybe too much gum causes granulation of color in the highlights, not just
too much pigment.
Kosar's book was worth every penny I paid for it getting it used from
abebooks.com (gasp). His 60pp chapter on dichromated colloids is wonderful,
but worth even more is his bibliography wherein patent numbers are contained
for further research. I'll be researching now til the cows come home.
Yesterday I tested side by side the theory of Z not using any gum
arabic added aside from what we would use in modern day tube paint (just
tube paint which presumably has "enough gum and no more to hold the pigment
together"), vs adding the gum arabic 1:1 as I read it in the text, both with
4x sensitizer; vs Livick's high paint and 1:1 sensitizer. I used a color
classified as non staining so I wouldn't sway the results. TOTAL stain with
the no added gum. Unusable at both times I exposed. The next Z method, gum
added 1:1 with tube pigment and high sensitizer (4x) was still stained, but
mildly acceptable. Livick's was fine. Not to say that this is a valid
test, and only several prints! But the exposures of the 3 side by side
were equally dark in the borders, the only difference being the complete
degradation of highlights that went from total degradation to sort of usable
degradation to acceptable highlights.
I also tested sensitizing the paper, drying, and putting a layer of
pigment and gum on top (one of Wall's ideas) and it worked--weird. Didn't
expect it to, thought the layer of top paint would all swoosh off, not
conceiving how it would intermingle with the layer of dichromate below, but
it did. Go figure.
Chris
>
> Your comments on relative humidity are especially interesting. For
whatever
> reason (much lower humidity and/or higher PH water?), my gum exposures are
> noticeably longer here in Wyoming than those made in New Jersey - with all
> other variables being the same.
>
> Best regards,
> Cactus Cowboy
> Big Wonderful Wyoming
>
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