Professor Owen's chemically tempered glass demonstration

A piece of bowed chemically tempered glass that could be flattened by hand without breaking, demonstrating favorable compressive surface stresses. Name uncertain ("Owen" or "Omen").

Professor Owen [?] when I was a student had a piece of chemically tempered glass that had compressive residual stresses. It was bowed, it was an eighth of an inch thick, and he could put it on the table, and he could flatten it with his hand — three inches over about 15 inches — and it wouldn't break, because it had favorable compressive residual stresses. I'd love to have that sample. I'd probably wear a pair of gloves when I did it, because one day it's liable to have a defect or a scratch, and all of a sudden it's going to shatter, and cut my hand. Nonetheless, you don't want to have any residual stresses, or if you do, you want favorable residual stresses that are compressive on the surface, so you have to overcome the compressive stress when you're bending the glass.