This tip will help you to avoid Red fireflies on blond hair using V-Ray.
No that’s not the title of my next novel. It’s a vray bug that plagued us for a while now. Whenever we digitally grow hair for our 3D models and collapse it down to poly strips with opacity maps sometimes, especially with blond hair for some reason, red fireflies appear!
After trying everything that seem to makes sense I started trying everything that did not make any sense which is always a proven method for everything that has to do with computers or software. And lo and behold: boosting the RGB Level of the opacity map kills the fireflies! Although I am sure there is a completely logical reason for it (and I would love to hear it!) for now I am satisfied with the solution.