I've been reading yours and others emulsion formulas in this forum, and I'm very interested in making my own emulsion, for papers. I really want to find a simple recipe of enlarging paper emulsion which doesn't need washing and that I could coat on artists canvas, too. In a brazilian book (Formulário fotográfico, by Reinhard Viebig), I found this one, and I wonder if you could give me tips or see if it will do the job. I'll translate the recipe:
Emulsion for Papers:
To emulsify any paper, you should first coat a layer on the support to be emulsified, with a fine brush or sponge. This layer consists of the following formula:
Potassium Iodide - 13,0 g
Potassium Bromide - 75,0 g
Starch - 17,0 g
Water to make - 1,0 liter
The emulsified paper, when dried, must be sensitized in the following solution:
Silver Nitrate - 50,0 g
Distilled Water - 1,0 liter
Let the paper float on this liquid and put it to dry in a dark place. Exposure, developing and fixing follow the normal processes used for ordinary bromide paper.
I found it interesting because it doesn't need washing as (I think so) the precipitate will fall on the Silver Nitrate solution container. It is not said, but I suppose that a starch glue should be made from the starch, and that will adhere the KBr and KI to the paper.
Do you think if I add some Thymol to the emulsion, its shelf life will be greater? Also, do you think it's a good idea to add the Silver Nitrate solution to the emulsion solution with more starch glue, and then coat it on paper/canvas, without washing?
Here in Brazil, it is impossible to find photograde gelatins, so this emulsion is very convenient, since it's easy to find cassava starch in the market.
I hope you can help me.