Re: Foxlee Gum Process

I know, I said I was finished.... But what with all the dense smoke this
topic created, and the confusing twists and turns, I fear the important
point I've tried to make may be missed. So just a quick summary:

The suggestion was made by Foxlee (let's just leave Marion out of this
altogether) that it is possible to create a faint image with dichromate
and sizing, then put undichromated pigmented gum on this and weight it
down, and you will get a pigmented image without exposure, as the result
of a reaction between the exposed dichromated colloid and the new
unexposed colloid.

The idea that there is a dark reaction that would act only on the image
is not consistent with anything I know about dichromated colloids. Joe's
suggestion that it may be a negative thing, where the dark reaction acts
on everything BUT the image, makes sense although neither of the
descriptions of this kind of image-making has included that rather
important fact if that's the assumption that this rests on.

If an image where the gum is apparently hardened only in the image and
not in the unexposed areas does result from this procedure, it must be
due to some other cause, rather than the explanation given; it could be
Galinsky's speculation about pressure, or it could be Joe's speculation
about lithography, but the main point that I don't want to be missed, is
that the probability that it's a dark reaction that acts only on the
image and not on the rest of the colloid is extremely small, approaching
zero in my opinion.
Katharine

Dave Soemarko wrote:
>
> Or put it differently, what Marion did was basically a "dye transfer," with
> the following exception:
>
> 1. A dicrhomated gelatin sheet, instead of a bleached bromide print, was
> used as the matrix.
> 2. Dicrhomate, instead of dye, was transferred to the second gelatin.
> 3. It was done in "dry" state rather than wet state, but gelatin can retain
> moisture.
>
> What Gallinsky did was:
> 1. Read Marion's paper incorrectly.
> 2. Subsequently deviced an incorrect test.
> 3. Made an incorrect conclusion.
>
> :-)
>
> Dave S
>
> ----- Original Message -----
> From: "Dave Soemarko" <fotodave@dsoemarko.us>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Thursday, June 24, 2004 2:14 PM
> Subject: Re: Foxlee Gum Process
>
> > I probably should not say too much, but if I only read from the
> information
> > below, I think in the case mentioned, Gallinsky probably just
> misunderstood
> > Marion's writing, and she subsequently did a wrong test and so she
> couldn't
> > duplicate Marion's observation (though from Marion's writing sounds like
> > s/he probably didn't quite understand what was really happening either).
> >
> > What Marion did was to exposed the dicrhomated gelatin *UNDER A NEGATIVE*,
> > so the exposed parts get hardened, but there are unexposed parts with
> > unhardened gelatin and dichromate left. When another piece of
> undichromated
> > gelatin is placed in closed contact with the exposed gelatin, the leftover
> > dichromate hardened the undichromated gelatin. The amount of leftover
> > dichromate is proportional to the exposure, which is inverse proportional
> to
> > density of the negative, so Marion got an image. I think humidity would
> help
> > here, but we don't know the condition of Marion's lab.
> >
> > In Gallinsky test, she exposed dichromated gelatin until maximum
> > insolubility! The is no leftover dicrhomate, no unhardened gelatin which
> to
> > retain some moisture. No wonder she didn't get any image. But then her
> > conclusion is about squeezee! That is an example of how we sometimes make
> > "logical" conclusion but might not be right because not all the parameters
> > or information is known.
> >
> >
> > Dave S
> >
> > ----- Original Message -----
> > From: "Katharine Thayer" <kthayer@pacifier.com>
> > To: <alt-photo-process-l@sask.usask.ca>
> > Sent: Thursday, June 24, 2004 6:30 AM
> > Subject: Re: Foxlee Gum Process
> >
> >
> > > Chris,
> > > This is quite similar to Marion's 1873 (Phot News 17:242) observation.
> > > described by Galinsky in 1930 (Biochemical Journal 24: 1706-1715) that
> > > "if a dichromated gelatin film which had become insoluble by exposure to
> > > light under a negative were placed in contact with a similar but
> > > unexposed film and the two were squeezed together under pressure, the
> > > gelatin in contact with the exposed gelatin became insoluble after 8-10
> > > hours and a print of the image was obtained. It was concluded that once
> > > action was set up by light in a dichromated gelatin film, this could
> > > induce the same change in gelatin placed in contact with it, without
> > > exposure to light.... The present writer attempted to reproduce this
> > > change in the absence of any mechanical influence, and found that no
> > > such alteration occurred."
> > >
> > > She exposed dichromated gelatin until maximum insolubility had been
> > > produced, and then added a gelatin coating and left the whole in the
> > > dark for 24 hours, then for two weeks, and then four weeks, and found
> > > by analysis that there was no change in the added gelatin regardless of
> > > the length of time it stayed in contact with the exposed gelatin. She
> > > concluded that a more probable explanation for Marion's observation was
> > > that the squeezing caused the insoluble material to impregnate the
> > > soluble gelatin in contact with it, thus making it more difficult to
> > > dissolve, although there was no actual change in the added gelatin
> > > itself.
> > >
> > > Katharine
> > >
> > > Christina Z. Anderson wrote:
> > > >
> > > > This list has been so darn quiet this week I figured I might as well
> > post
> > > > another historical gum blurb!
> > > >
> > > > This is the oddest process, so just a point of interest that
> maybe
> > > > relates to nothing, or maybe something. It is the "indirect pigment
> > image".
> > > > Sized paper, gelatin.
> > > > paper sensitized with a 2.5% pot bi.
> > > > Paper exposed.
> > > > Paper developed so nothing remains except a faint positive.
> > > > Paper is dried, and can be pigmented right away as per below, or saved
> > for
> > > > weeks later.
> > > > To pigment: 5 parts 40% gum to 1 part glycerin to 2 parts acetic acid
> > to
> > > > 8-10 grains dry pigment.
> > > > Coat and dry the paper, leave under pressure for 30-36 hr, like under
> > books,
> > > > and then cold water develop, no exposure. It'll automatically develop
> in
> > an
> > > > hour.
> > > > Based on, get this, Foxlee's idea that the action of light set up in
> one
> > > > colloid is transferred to, and continued in, another which is not
> > exposed to
> > > > light at all. (mind you, no bichromate has been supposedly washed out
> > in
> > > > the water). Foxlee prefers to use starch as the sizing colloid, but
> > Griffin
> > > > prefers gelatin.
> > > > Advantages: no rush to develop. Pigmented coat not printed thru so it
> > > > doesn't need to be carefully applied. Hardening from bottom up, so it
> > is
> > > > more durable.
> > > > Weird
> > > > Chris
> > >
> >
Received on Thu Jun 24 17:13:20 2004