Dear Lydia,
What do you mean for "printing on watercolor paper"?
There is a technique, mostly used in the second half
of the past century and still alive today for very
special effects, which is called GUM PRINTING.
It is a contact printing technique, and requires the
preparation of some reagent mixtures, based on potassium
or ammonium dichromate, a pigment and arabic gum.
The mixture is coated onto a paper sheet sufficiently
robust like coarse watercolor paper, dried, and expose
under a negative to an ultraviolet light source, or to
the sun. This latter is very variable, and creates some
problem in the definition of the exact exposure time
(which is of the order of 5 to 20 minutes in any case).
The exposed paper is then immersed in water at room temperature
and left in it until the unexposed or less exposed parts of the
print dissolve. The paper is then dried.
I have some limited experience, and I am experimenting
with this technique, which gives even for beginners some
interesting results.
But before attempting any test, answer me.
I will send you more advises, and list some books where
to find formulas and chemicals source, as well as the
precautions to take when using them.
Looking forward to have an answer from you and finally
find someone interested in this topic, I send you myù
Best Regards
Salvatore Previtera
1. Using a prepared sensitiser like Liquid Light
2. Platinum/paladium process
3. Carbon transfer process
4. Bromoil transfer
5. Gum bichromate process
Cheers,
Gene Laughter