Jack Fulton asked if I would post a formula for the thiocarbimide formula I
mentioned in an earlier missive.
There are numerous formulas to be found (more or less similar), but I've
been using a formula listed in the back of Eddie Ephrams "Creative
Elements." It is is first mixed in two separate stock solutions:
Part A is a 10% solution (100 grams per liter) of Thiocarbimide (also
called Thiourea) mixed at 40* C.
Part B is 10% solution of Sodium Hydroxide mixed at 30*C.
To use this toner, first either completely or partially bleach the print in
a "standard" (ie Kodak Sepia Part A) Potassium Ferracynide/Potassium
Bromide bleach solution.
Wash the print for a couple minutes in running water and redevelop in a
working solution of the thiocarbimide.
Working solution ratios can be varied to effect significant color
differences.
Sol. A Sol. B Water Image color
10ml 50ml 500ml Purple-brown
50ml 10ml 500ml Yellow-brown
Varying the ratio between A and B will render shifts between those tonal
colors.
* PLease note that Sodium Hydroxide is nothing other than RED DEVIL brand
Lye, available in any grocery store. I recommend saving a few bucks and
purchasing it there (sorry Dick) as there's no difference in the quality
which you will receive from a chemical supply. I use the grocery store
stuff successfully in all my workshops.
* Please also note that thiocarbimide has been linked to cancer in
California. I mention this because Jack lives in California and might want
to wear gloves when using this toner - something I recommend as a general
rule when using any toner.
Good luck-
Jon Bailey
St. George, Maine