Yup - that works. See the attached image. I took a file that I had and brought up the skin texture for the face. I then added a procedural material on the B channel, and changed it to pure color (bluish). I then selected AB mode. Note that the procedural material has an alpha element (the triangles) that's left over from the random material that was created. Its not referenced or used so it doesn't matter. Note also that the sphere preview implies that the coverage is uneven, when its not in the final render (the inset image). Hope this helps! TomD