I want to _measure_ knife sharpness. In a repeatable, scientific
way. And preferably, non-destructive to the sharpened edge!

Shop teacher 60 years ago taught measuring sharpness using a simple yet
scientific method. Look at the edge! Yup, just look at the edge, straight
on, under window light. If you can see the edge, it's not sharp.
Worked then and works now.

Old Chief Lynn