Re: Foxlee Gum Process

From: Dave Soemarko ^lt;[email protected]>
Date: 07/15/04-07:41:31 PM Z
Message-id: <010501c46ad6$058b0900$0500a8c0@wds>

> 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.

As I have argued in Marion's case, it depends on the remaining dichromate,
so you have developed the image, you will not get an image, so I am not
surprised that you didn't get an image.

As I have argued in Foxlee case, the action is mechanical (ink sticking to
the hardened image). Since you have no ink at all, I am not surprised that
you didn't get any image.

> 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 Thu Jul 15 19:42:36 2004

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