Testing for Overheated Edges

[grepper]

(2) If the temperature increase is greater than indicated by the Tempilaq is it sustained for a period of time long enough to soften the steel significantly?

I too have that question.  If we were to assume there is heating, I would think that it would occur at the very thin apex of the blade.  This super thin metal would heat and cool extremely rapidly.  I think the whole process would occur in only a second or two.

I think that for all intents and practical purposes it is irrelevant for general sharpening, but sort of interesting nonetheless.