White and Pink Pearls

I had an instructor at the Art Institute of Pittsburgh that despised the use of Pink Pearl erasers. If he caught anyone using one in his class, he would snatch it off of their desk and throw it across the classroom. He was an evangelist of kneaded erasers, and hated the dreaded “pink streak” that Pink Pearls are notorious for leaving behind in their wake of pink crumbles. But it wasn’t until recently that I discovered that there are White Pearl erasers — no more pink streaks [I think]! I wonder if a former student of his invented this version . . .