# Communities > Modern-era Swords and Collecting Community > Modern Production Katanas >  Clay Hardening a Through Tempered Blade (after the fact)

## Thomas Nguyen

I'm sure this question has been asked before but for those in the know, is it possible to clay temper a through hardened blade?  What I'm asking is if I have a through hardened blade that I really like and it isn't offered with clay tempering, is it still possible to do it and have it repolished to get a hamon and the benefits of differential hardening? I already know it isn't cost effective but if you had no other choice.  If it can be done, who does it?

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## Angelo Silva

Well... Possible? Yes! Desirable? Nope.

The thing is, you can normalize and re heat treat the blade, but since its probably sharp it will most likely snap with the new heat treatment, so it would have to be blunted quite a bit which would change the shape and dimensions of the blade. The DH could also induce a different curvature to the blade, so it might not look anything like the blade you enjoy now.

A good smith could work from it, as reforging blades isn't unheard of, but it would probably look nothing like the blade you have now. Hope it helps.

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## Angelo Silva

Double post.

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## Thomas Nguyen

Thank you Angelo. I really appreciate your insight on this.

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## Angelo Silva

Thomas, you can send a PM to Aaron Justice. He had a nihonto re heat treated. He can give you a better idea of what will happen.

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## Thomas Nguyen

Thank you Angelo. I'll ask him next time I see him.

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## Bill Sheehan

Hi Thomas

I would say with what limited knowledge I posses, your best option would be to follow the path that Angelo suggested and send your blade to a smith and have that smith use your blade as a model to work from. You may also find once you start down this road you may opt for other enhancements like a folded steel blade for hada as well.

Sincerely
Bill

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## Stefan L

There is a technique for what was called a softback, involves heating to spine of the blade.  It is difficult to "not scew up" and hence not recommended.  I tried it on a forge welded knife that I repaired and yes, I screwed it up.  Honestly, I would suggest that you purchse a blade that was originally done.

Just my .02

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## John w Smith

Oddly enough Aaron Justice I believe has the nihonto that I reclaimed or re-heat treated.  I was successful in my attempt and I have also re-heat treated a production blade successfully as well.  Plus I did a Tanto that was a production blade for a forum member to whom his name escapes me at the moment.

So in short yes it can be done, however you will loose some width on the blade as I would need to get some meat on it to keep it from cracking.

Plus there is the unpredictable result of loosing sori or gaining more sori.  The Nohonto that I did and two production blade had no loss or gain, but I did and this is the odd part heat treat a blade I forged for s customer and it had almost an inch of sori, and I lost all of it in the quench.

So sure I can try but just keep in mind the pit falls.

John

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## John w Smith

Plus keep in mind as to what type of hamon you want, if it is crazy then you can get into trouble with warping and or cracking




John

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