I remember Kachel mentioning (maybe in Darkroom Techniques) that color of light does influence an emulsions response. A traditional emulsion gains contrast when exposed with strong red light, (as when exposed through a 25 red filter), which is what I found in my tests and, if memory is serving me right, new technology films lose contrast. Might be worth keeping in mind if you're exposing under a color head. Good luck. DJ(posted 8669 days ago)