Re: tonal inversion and pigment loads

On Jan 28, 2006, at 9:24 AM, Tom Sobota wrote:

> Sorry, Katharine, I have posted this image some weeks before with a
> clearer explanation of what it did mean. But taken out of
> context it is perhaps not very illustrative. Never mind, I'll try
> to organize this material better so it's easier to follow and
> understand.

Well, I'm pretty sure I responded to this in context when you showed
it before, so maybe my response from then would be more illuminating
than my present puzzlement, who knows.

>
> Yes, living next door would be easier since surely we are looking
> at the same things and calling them different names. On the other
> hand, since you seem to be a woman of strong convictions, perhaps
> living in Madrid is safer for me :-)

Gosh. I say what I think, but I've never yet killed anyone, or
even hurt anyone; I'm not considered particularly dangerous by those
who know me, and my next door neighbors aren't afraid of me, in fact
they like me. So you really needn't fear for your safety living
next door to me.

>
> You know, I have been thinking about the fact that you have seldom
> found inversion in your previous work. Even these days
> in your tests, as far as I see, you seem to get easily pigment
> stain but not inversion.
>
> In my case it is very different. I get inversion when I want it,
> with different papers and pigments. With normal negatives and
> subexposition, or with Stouffer tablets, as you have seen.
>
> In a nutshell, I wonder if the very different conditions of
> relative humidity and temperature could make a difference. I gather
> that
> you live somewhere on the West Coast up north, not sure if in the
> U.S. or Canada, but certainly very humid. I live in a very
> dry country. Gum is sensible to humidity, as Kosar dixit. It is a
> wild guess, but I wonder ...
>

Yes, I too have been thinking about how complex this is, and you
could be entirely right about the humidiity and everything. But just
to introduce more complexity into the mix, here's another wrinkle:

Since the thing I was planning to do today was canceled because of
the weather, I thought well, what better way to spend the day then
to make a grid of test strips, varying exposure, pigment load,
sizing, see if I can discover the point at which I can reliably make
an inversion happen. So from the test strip I showed last night, I
decided to go both ways, less pigmented and then more pigmented.
First I cut the pigment in half and got a fairly good tonal scale,
with almost no stain, but a very light stain. So then I thought well,
this isn't a very heavy pigment load so maybe this stain really is
paper/sizing related, rather than pigment-related. So I printed the
same mix on a piece of the same paper I had that was sized with more
than the amount of gelatin I usually use. It turned out this size
was too heavy, and the emulsion flaked off right away. BUT, under the
flaked-off emulsion was a significant stain, more stain than on the
less-sized paper. I always seem to want to try to save an image
that's disappearing, so I grabbed it and dried it fast before the
last two steps flaked off, but afterward I thought that if I had left
it alone, all the gum emulsion would have left and there would would
be just stain and gum resist where the gum flaked off. I've tried
the same mix on the same paper several more times, at longer and
longer exposures, with varying (but not predictable) results, but
always the stain and partial inversions where the numbers came off,
and most crucially, always the flaking off of much of the gum
emulsion due to the too-heavy size, which would be the ruination of
this combination anyway, so there's not much point in pursuing this
particular line of inquiry further.

This doesn't change my current feeling that inversion is a special
case of stain, and that stain is related to either paper/sizing or to
pigment, but I wouldn't have thought that a sizing problem would go
in this particular direction: more sizing equals more stain. I do
know from experience that more sizing causes flaking, but I've never
seen it cause stain at the same time. I've posted the results from
this mix on normally-sized paper and the first one I did with the
same mix on on the more heavily sized paper (the others are still
drying) along with the more pigmented mix from last night.

http://www.pacifier.com/~kthayer/html/missingnumbers.html

Carry on,
Katharine
Received on Sat Jan 28 14:35:21 2006