Cold light and Pyro

[Brian Ellis]

"Without affecting" is a little extreme but the basic idea is accurate and it's pretty much a universal principle, not confined to cold light heads. Burning at low contrast, whether with a color head, a variable contrast b&w head, or a filter will affect the highlights much more than the shadows. And burning at a high contrast will affect the shadows much more than the highlights.

[Drew Wiley]

VC papers aren't perfect, but they are vastly better than they once were, and seem
just as good as the very best graded papers. But they rarely respond well to low
contrast filtration exclusively (Y or G); you need to punch in a little M or B. On the other hand, I have had several papers respond well to high contrast filtration only, provided the negative is appropriate for this. Often rather than true split printing, I will use some overall white light exposure first, then simply punch the highlights or shadows with strong filtration afterward. Of course this can be done selectively through burning in specific areas if needed. Many light sources aren't perfect either,
but for all practical purposes it is safe to make certain generalizations. With practice
it's quite easy. In fact, I don't even think about it much any more. I can switch back
and forth between different light sources almost subconsciously, although I generally
keep my two true additive colorheads immaculately clean for critical color printing,
where the distinction between additive and subtractive sources is more apparent
than in black-and-white work.