Re: Foxlee Gum Process

> No, I'm not. And in fact on re-reading this section very carefully, I'm
> not even sure your interpretation of what she did is not more correct
> than mine. But that doesn't change the fact that if your interpretation
> is right about what's going on, then the image in Foxlee's or Marion's
> experiment could not have been retained because the unexposed areas
> would become insoluble.

I replied about Foxlee's process separately. I think, again it is just my
opinion, that Foxlee uses a completely different mechanism. In the Foxlee's
process, the oily ink sticks to the insoluble gelatin, but the print is then
immersed in water again, the soluble gelatin absorb water, and water repels
oil, so this part get cleared. This is more closer to gumoil (except that
rather then immersing in water, the print is cleared by wiping, but the
principle is similar, the oil attached stronger to the insoluble part
because there is no water whereas it is more readily to be wiped off from
the soluble gum part), or similar to acrylic-gelatin method that one wrote
in Photo Technique (except that there the principle is the acrylic would
attach itself to the insoluble part, whereas the soluble gelatin is washed
by HOT water). In this case (Foxlee), it is another clever use of the same
concept except that oil-water characteristic is utilised.

And the acid in the formula really gives away. If you compare that with
lithography, you'll notice some similarity in the mechanism. Also, the
glycerin might not be synthetic glycerin where it is technically alcohol. It
could be glycerin made from vegetable or animal skin, so it has fat/oil
content. Acid breaks the oil so that it attaches better to the insoluble
part, just like in lithography.

> As I've said, I don't think your explanation works because
> it predicts that the entire print would become a wall of insoluble
> colloid, rather than the image being retained.
>

If you assume that even the insoluble part still has enough dichromate to
harden the other gelatin sheet, then the whole print would indeed be a wall
of insoluble colloid; but my argument is that the insoluble is not really
playing much, if at all, it is the insoluble part that comes to play; that's
why one would get an image.

And I am thinking that it works similar to dye transfer, since the first
gelatin sheet is hardened proportional (from the top), the dichromate will
get into the 2nd gelatin sheet in proportional thickness as well.

> personally, never did and never will. When I speak of an "argument" I'm
> using the term in the sense of a position that's laid out, or a point
> that's been brought forward, not a fight, for crying out loud.

That's great! :-)

>
> That's exactly as the reference is given in Galinsky, so that's the best
> I can do.
>

Well, I found that U of Michigan didn't have either Phot New, Photo News, or
Biochemcial Journal. The Biochemical Journal they have, but on earlier
copies, they don't have complete issues; and as always, they miss the one I
need (they have some 21, 22, 23, but no 24!) I guess I will have to let go.

Dave S
Received on Thu Jun 24 14:47:10 2004