Quote Originally Posted by 25asa

This is the most fascinating reading on the site!!
It's a mind opener! I've always wondered how film was made.
Might even try to do it myself.

Is it a dye that sensitizes a film for infrared? If so, what is it?
Yes, a dye sensitizes the film. A particular dye is selected for each major region of the spectrum from blue to green to red to infrared.

These are probably the most costly and hard to get of all of the ingredients used to make emulsions.