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Is this a Hamon? If not then what?

Posted by fugglesby 
Is this a Hamon? If not then what?
October 17, 2017 12:30AM
Hey guys!
I've been teaching the guys in Nepal some new techniques and I've had them experimenting with different Patinas and acid treatments.
This blade here was dunked into boiling vinegar, taken out and had the scale rubbed off then dunked again. A nice even darkness all over, except along the edge where it's significantly darker.




Now my initial thought was cool, we edge quench our blades and this has brought out the hamon. It's the same shape on both sides but doesn't quite make sense. For starters it's a fair bit lower than I imagined the hamon line would have been. More importantly it's darker than the steel above, not lighter as you'd usually see. Steel is 5160, oil quenched and tempered. Could this potentially be an artifact from the etching process? Some area which was more greatly affected due to the edge acting as a nucleation point for bubbles or something? Or has this steel somehow lost chromium or through some other method lost corrosion resistance along the blade edge?
Any input or discussion welcome. I'm pretty lost on this one.
Re: Is this a Hamon? If not then what?
October 17, 2017 08:49AM
Ref :

[www.bladesmithsforum.com]

It short, it is likely a hamon, dark due to the etch vs traditional polished which reverses the light/dark contrast.
Re: Is this a Hamon? If not then what?
November 01, 2017 06:01PM
Thanks a heap cliff! Lots of great info in that thread and things for us to experiment with.
Re: Is this a Hamon? If not then what?
April 22, 2020 12:25PM
I guess maybe an update is due. This was indeed a hamon and proved to be very repeatable and a great surprise.
Somethin I didn't mention earlier- a big reason i didn't assume this was a hamon is that 5160 has a reputation for producing very low contrast and poor hamons. The fact that it's comparatively low carbon and also deep hardening might have something to do with this- it's hard to get a dramatic line of contrast on something that's a bit more vague. However upon further experimentation we've been pulling better and better hamons out of our blades through acid wash.



Note the contrast here but also the whitish line showing up (forgot the japanese name). This kind of activity I haven't seen in other 5160 blades. The question is why? two theories- a lot of the discussion regarding hamons comes from japanese techniques which use polishing techniques to show hamon. 5160 being a popular material for hard use katanas etc. Perhaps the different structures in 5160 just don't show up as well from polishing. Second theory is due to the process we use. In Nepal we don't have access to ferric chloride or any other common etchants so we have to use much weaker household acids. This takes a lot longer (up to an hour or more) and requires frequent gentle scrubbing to knock off any protective oxides or reddening on the surface. Maybe this unorthodox method helps bring out contrast in very mild activity? A question for someone smarter than me.
For the timebeing though just stoked we can make kukri hamon as dope as this.

cKc
Re: Is this a Hamon? If not then what?
April 23, 2020 12:45AM
very nice. my only concern is with the depth of hardening in some locations. if you get edge damage you could lose the life of the knife completely

in the khukri it looks very shallow near the handle and tip. on the blade above it looks like you loose an inch of blade at the handle with no hardening at all. is this an illusion of the image?

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It's not Cliff, its Dr Stamp
#kebabstickcut, it's a thing - make it happen
cKc
Re: Is this a Hamon? If not then what?
April 23, 2020 01:00AM
Quote
fugglesby
Note the contrast here but also the whitish line showing up (forgot the japanese name).

TBH Who cares what the japanese term is.. i dont speak japanese, and edge quenching of knvies is not a japanese invention. it just happens that being japanese they have words for all the things we do in english.

aside from that.. lol

what would be interesting to know is if you are forming bainite or pearlite at the transformation line. it would depend on how slowly the different parts are quenching.


if you could work out a quench that is martensite edge with a full bainite spine and blade then you'd have one very tough blade.

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It's not Cliff, its Dr Stamp
#kebabstickcut, it's a thing - make it happen
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