Re: Van Dyke Contrast

Judy Seigel (jseigel@panix.com)
Fri, 21 Jun 1996 00:35:08 -0400 (EDT)

On Thu, 20 Jun 1996, Risa S. Horowitz wrote:
>
> how long do you give for VD first rinse? I made a comparison once between no
> rinse and two minutes rinse, and the difference in the contrast of my prints
> after put thru the S.Thiosulfite was HUGE. I hadn't understood till then how
> flat the residues would keep the prints if not rinsed first.
>

If you absent-mindedly put your vandyke print directly into fixer without
rinsing it first (as has been known to happen), for some probably adequate
chemical reason, the print will bleach out almost entirely. Whether very
brief rinsing induces a modified version of this bleaching I don't know,
but I do know it's trouble....

> About the process below, how long is too long for the print in the sun. Does
> the printing out after bleaching stop at some point???
>
> >Bleach a b&w print with a bichromate and hydrochloric acid bleach (lab
> >manuals should have a few formulas). Wash, dry. Expose in sunlight. Image
> >will print out a nice brown color, depending on paper. As I understand it,
> >you now have a silver chloride print -- or a semi. It may take a few days
> >or a week. I did this through the window. No need to leave the print in
> >the camelia bush.

I suppose the print will keep printing out until all the silver halide has
been re-reduced to metallic silver. But remember, print has already been
fixed, so it's not going to turn all dark in the highlights. The areas
that were dark in the original print (before bleaching) will go dark again,
though brown not black, and there will be some intensification from the
bichromate (as in chromium intensifier).

Judy