I am cross posting this from the diazo thread:
Originally Posted by keesbran
"...does the original Ultrastable recipe contain other special ingrediŽnts like surfactants or conservation agents?
And how about sugar/glycerin/alcohol (amounts) or other plasticizers in the pigmented gelatin?"
The "recipe" for the UltraStable pigment films is based on (except for the sensitizer) the formulation published in "The Home Manufacture of Materials for Carbon Printing" ( Wm. D. Fleming, American Photography, Vol 32, 1938, August, No. 8) :
Gelatin (20%) 100 ml
Sugar 5 g
Glycerin 1.5 ml
Pigment 1-5 - 2.5 g
Thymol (10% solution in 95% alcohol) 5 ml
Water (to make) 200 ml Total
Surfactants were added to the emulsion to facilitate machine coating but are not necessary for hand-made materials.