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Sal'

Interrupted quench question.

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Hello everyone, my name is Sal’ and I operate a small little adventure mounting and restoring Japanese blades. Everything from simple tsuba-make to full Koshirae. Been on here lurking for quite some time now. Been slowly getting ready to start forging and had a question about interrupted quenches. Currently I do most of my work traditional mounting others work for Japanese style blades and nihonto, but want to start  asking and using my own blades.

I will be forging Japanese style blades with 1075 to start. All under 15 inches in total length. My plan is to start in either heated water (heated but still able to put my fingers in) or brine for a quick 3 seconds ( or more if that is ideal without too much risk) in a horizontal quench tank I’m building and then finish the quench in heated parks 50. Hoping to get the visual benefits on the Hamon from the water and then HOPEFULLY not crack it with the help of parks 50. 
My question is, for plunging into the parks 50, can i still plunge it down vertically? I would assume yes but want to be as sure as one can. And can this method still work as my blades get longer as well? Do I still assume and plan for negative sori with an interrupted quench from water into parks 50?

Thank you all in advance for any help!

Sal’ of Jizamurai Customs

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Parks 50 is overkill for this, and may be counter productive - the idea is to get the blade past the pearlite nose and to Ms  as fast as possible, and then slow everything downas much as possible  before you get to Mf, so I just go from water into cold veg oil.  Quenching into the oil vertically is no problem, and makes no discernible difference. Sori is difficult to predict - in general water to oil will produce positive sori, but maybe only half as much as a straight water quench. That said, all sori  depends on a bunch of variables - geometry, quenchant, clay layout, quench temp, quenchant temp, etc. Even in water, it is possible to produce mu-sori and uchi-sori.  To produce maximum sori in water-to-oil, you want to hold in the water until the down curve has finished and the blade is starting to curve up, then move it to the slower quench as fast as possible...

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I've yet to get a negative sori from quenching a kitchen knife in oil. I believe the blade geometry also has it's word on it, and the thin and wide kitchen blade will not bend up or downward easily. 

 

Also, I would not use p50 for interrupted quench. That oil is a bit pricey to mix with water and warm canola would be just fine, since the water will take care of the pearlite nose. Keep your p50 for oil only quench.

 

Lastly, I would begin with oil quench first. P50 will get you full hardness and is much less risky. You can also get a nice hamon with p50 only. Not the absolute best activity but I believe it's not what you should focus on with your first blades.

 

Just my two cents of course

 

D'oh! Jake beat me to it

Edited by Joël Mercier
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Thank you both! There is just so much to concern oneself with and get lost in so many details, so many variables at play. I did have questions about accidentally mixing some water into the oil but didn't want to throw too many questions into the mix at once :) 

 

Should I go ahead and just get parks 50 to start with if its within budget and do an oil only quench to start?? Or go the canola oil route first? I do plan to use other steels in the next year or so like 1095 and W2.

 

Mostly starting with tanto like Yoroi-dōshi, Hira-zukuri, etc. I'm sure gyutou and santoku will follow, as everyone I know is already asking me for them, but I'm trying my hardest to focus at first on Japanese tanto.  I plan to start with thicker blades in general with forging and as I become more comfortable move to thinner kitchen knifes.

I uploaded some pictures of a blade by Kubo Yoshihiro that I created the mounts for, minus the antique menuki. 

Cheers,
Sal' of Jizamurai Customs

tsugarunuri3.jpg

tsugarunuri4.jpg

tsugarunuri5.jpg

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1075, 1095 and W2 are all shallow hardening steels so getting the proper quenchant is a good start. 

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I have had fine luck quenching Aldo's low-Mn 1075 in hot water, but I've only done a couple of tantos.  Kitchen knives might risk cracking.  I would not recommend Admiral's 1075, it has twice the Mn level and is thus more likely to crack.  I would not attempt 1095 or W1/W2 in water.  Well, I did attempt a W1 kitchen knife in water.  I still have the pieces somewhere...

 

Have you read this thread?

 

Not for the faint of heart, but it works.

 

 

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I've done a few brine to oil quenches in 1095, but like Alan, all of my attempts to do the same with W2 have resulted in broken blades.

 

Common bladesmith lore is that brine is technically faster than water, but at the same time, not quite as harsh.  I actually don't know if that is true or not.

 

The hamons I have achieved have been rather boring.  I've learned that there is much more to getting a nice hamon than slapping some clay on shallow hardening steel and quenching fast.  Unfortunately, I haven't yet learned what else is involved :lol:

Edited by Brian Dougherty
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