WOW this should be a sticky. I have been testing the SS4 cutting cardboard trying
to dull it and have not even got close. We may have to develop harder tests for the scrapyard knives because the old measures take to long.

Through hardening is usualy tougher than differential. My cheness katana 9260 is
through hardened because it makes for a tougher blade than ones with a hamon although they are more traditional and better looking.