>How can I increase the contrast of my Van Dyke prints?
Mercury!
Bleach print in 5 gms mercuric chloride,
.5 gms pot bromide (That's 1/2 gm)
1000 mls water.
The proportions don't seem to matter much, I used to eyeball it out. The
above is from memory.
Wash in 3 baths of 5% hydrochloric acid for 5 minutes. It'll stain if you don't
Wash for 5 minutes
Re-develop in Dektol (that's right!)
Print will be a richer redder brown, unlike the deader chocolatey brown of
the standard Van Dyke and crisper contrast to boot. This formula is the
formula for Engraving Black toner From Neblette's Principles and Practice of
Photography 2nd Ed. This toner was designed to tone silver gelatin prints
black (that's right!). Now why did I try this on a Van Dyke? Well it was
back in the 60's, and was probably a chemically induced inspiration.
The silver in the print has been replaced with mercury, probably more
permanent than silver, can any archivist types out there confirm this?
Now what to do with the toner when you are through? Take it to a waste
disposal company. No, not in the neighbors fish pond!
Dick S.
Bostick & Sullivan
Platinum and Palladium
Photographic Chemistry
Santa Fe, New mexico