> I tried the given formula's and the effect on the
>gelatine started after adding some bleacher solution; it toke more than 15
>minutes,
The formulation from Sudre requires only three minutes for fiber based papers
for bleaching to the desired degree. In brief, start with a well washed
print. If the print was made some time ago, soak it first so the emulsion will
be softened.
The peroxide (25 grams) is based on 30 percent peroxide, not the 3 percent
found in the stores. If you use store peroxide, then you need 250 grams, and
use less water.
The second step is to wash well, then dunk in the used developer or into a
sepia toner bath. Time here is not critical.
In the final wash, I found I needed very little rubbing with a cotton swab to
get the desired effect. It is very easy to remove too much. Then rinse in
water.
Optional steps from here are either to re-insert into very used dektol for
three or so minutes, and then washed. Different developers and dilutions will
give various colors, and can be used in sequence if desired. Wash and air dry,
or tone if you want to try other colors.
Hope this helps.
Don