Quote Originally Posted by silverloaf View Post
Bruno-I was talking about "as quenched" hardness up to 64 with a proper soak in o1, not suggesting to aim for 64 as an end result. and Bruno- the statement on tempering as a stress relief- i agree wholeheartedly. its not just a matter of reducing the hardness, its about equalizing internal stresses as well. I do think ease of sharpening is better for anyone interested in maintaining their own blades. it seems a lot of folks have become obsessed with highest degree of hardness rather than ease of maintenance. it doesn't take an ultra hardened blade to achieve keenness and edge holding. sometimes its more a matter of ingredients in a particular steel that affect the ability to achieve keenness. sometimes its the manner of heat treat that means the most. will the particular steel benefit from multiple quenches or not in order to refine the grain size? lots of factors, but as hipsley said, if it takes an edge and shaves successfully then the proof was in the pudding. optimal does not mean essential by any means. the shave and ease of maintenance are the test of any blade.
Precisely,

This is why I go only for a 1 hour temper to start. Its because I can't be sure how optimal the hardening has gone. The hone always informs me. This is purely a practical consideration over theory. If I get a very hard edge, one hour would not be enough and would relinquish more martensite. Chippy edges are another real problem if they are too hard, I can vouch for that.

Joe