this is what I found:

For those who wish to know. Straight from the horses mouth (Standard Textbook of Barbering, 1950, p. 23):

Testing the Edge


2. A stropped razor should be tested by passing it gently over the moistened ball of the thumb or index finger. A stropped razor should never be tested on the nail.


ok, here's the question. I strop my razor, pass it gently over my moistened ball of thumb, and then what? What is it that I'm to be looking for as I do this?

thank you