I am also interested in increasing the light response of colloidion emulsions. Could you use an inexpensive dye like eosin or erythrosine first and see if you get a better spectral response? My guestion is whether the dye goes into the colloidion mix ,the silver bath,or a seperate bath altogether. My guess would be the colloidion, since the dye may react with the silver
You could add the dye to the pouring stock to save the main stock. About 2ml of a 0.1% dye solution in alcohol per 100ml sounds right from my gelatin work.

Any thoughts guys?
Rob