Re: Foxlee Gum Process

Well, as happens so often with these one-sample tests, my results are
largely uninterpretable and inconclusive.

There was one clear finding:no pigmented image or even the ghost of one
formed in either condition: pressure or no pressure. So at least the
laws of dichromated colloids are still working as I would have expected
and I don't have to eat crow, as I said I would if a pigmented image
appeared in the print that was not under pressure.

But I don't believe I've shed any light on the pressure question one way
or the other, and what's more I got a weird very faint light yellow
overall stain that I don't have any idea what it is. It looks like a
very faint stain of unreacted dichromate but doesn't clear like it
should if that's what it is, and it's not the right color to be a
pigment stain or a dark reaction. At any rate the stain is so very faint
that it wouldn't have obscured an image if one had appeared, but just
the same I don't know what it is, and that puzzles me.

Speaking of hexavalent chromium, this week's crime story from my neck of
the woods: someone who was mad at a dairy farmer killed some of his cows
and made others sick by splashing them with some hexavalent chromium
substance (the authorities won't disclose what it was other than
Cr(VI)). Anyway, something to ponder on while we splash around in our
tubs of dichromate; "this stuff could kill a cow." Cheers,

Katharine

Katharine Thayer wrote:
>
. With this I am testing neither Foxless's or
> Marion's methods but two general assertions: (1) that unexposed
> undichromated colloid can be rendered insoluble by being brought in
> contact with exposed dichromated colloid in the dark and (2) whether
> soluble pigmented colloid can be forced by pressure to stick to
> insoluble colloid to create an image that is made by mechanical not
> chemical means, as suggested by Galinsky.
>
> If a pigmented image forms in both conditions (a most unlikely outcome
> IMO) then Foxlee is right, and I will eat crow. If there is a dark
> reaction in both conditions, then that would provide support for the
> general assertion in (1) but not for Foxlee's claim. If there is no
> pigmented image in the print without pressure but a pigmented image in
> the print with pressure, that would provide support for (2) and no
> support for (1). As I say, what I think most likely is that the
> pigmented gum will simply wash off in both conditions (the fact that
> Foxlee adds other things besides the gum to make the stuff stickier
> suggests that it may not work with just gum and pigment alone) but we'll
> see. As I said, I'm not testing Foxlee's method, but simply the general
> assertion stated above in (1) and Galinksy's suggestion that Marion's
> result could be due to pressure alone causing insoluble and soluble
> colloid to intermingle. Marion didn't add anything to the colloid as far
> as I know, but h/she was using gelatin rather than gum, so of course
> it's not an exact test, but as close as I can get in a quick and dirty
> test of the two questions.
> Katharine Thayer
Received on Sat Jun 26 19:45:49 2004