Quote Originally Posted by David Lyga View Post
Much of potential problem comes when you use variable contrast paper which 'recognizes' colors as contrast indicators.
Not just that, also think of the orange mask. B&W paper is sensitive to green and blue light but only barely to red light, and orange won't give you much blue light.

The issue B&W prints from color negs has been discussed in many threads both here on APUG and elsewhere.