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Timo Nieminen · 16th March 2016, 10:32 PM

I don't think you can tell by the contrast how the differential hardening was done. Width of the hardened region, and pattern - especially fancy patterns - can give you clues.

Also length of blade. It's harder to do an edge quench on very long blades.

But, in the end, if the smith knows what he's doing, differential hardening with a full quench with clay coating (AKA clay tempering, even though it isn't tempering) isn't that difficult. Compared to a full quench without clay, you need more materials and more knowledge, but not that much more. And it makes tempering more forgiving, so the overall heat treatment can be more reliable.

For an interesting example, see
http://www.gunsite.co.za/forums/show...se-style-hamon
which shows some blades done with a combination of edge quench and clay coating. The dips and rises in the hamon have the same contrast - the dips are due to the clay, the tops of the rises are due to the edge quench.

Hamon from edge quench in wax:
http://edgematters.uk/thread/3117-blades-with-hamon/
A solid quench medium can make it easier to do edge quenching on curved blades. I have heard of fruit being used (traditionally).

16th March 2016, 10:32 PM	#16
Timo Nieminen Member Join Date: Mar 2012 Posts: 422	I don't think you can tell by the contrast how the differential hardening was done. Width of the hardened region, and pattern - especially fancy patterns - can give you clues. Also length of blade. It's harder to do an edge quench on very long blades. But, in the end, if the smith knows what he's doing, differential hardening with a full quench with clay coating (AKA clay tempering, even though it isn't tempering) isn't that difficult. Compared to a full quench without clay, you need more materials and more knowledge, but not that much more. And it makes tempering more forgiving, so the overall heat treatment can be more reliable. For an interesting example, see http://www.gunsite.co.za/forums/show...se-style-hamon which shows some blades done with a combination of edge quench and clay coating. The dips and rises in the hamon have the same contrast - the dips are due to the clay, the tops of the rises are due to the edge quench. Hamon from edge quench in wax: http://edgematters.uk/thread/3117-blades-with-hamon/ A solid quench medium can make it easier to do edge quenching on curved blades. I have heard of fruit being used (traditionally).