flare up question.

Jim Coffee

Well-Known Member
Hi Guy's. I recently changed my quench oil from canola oil to Parks 50. My first knife to quench in the Parks was a big bowie made of 1075. I wanted to put a hamon on this knife so I put Rutland furnace cement on it and went to heat treating it. I have a digital oven and heated the blade to 1525 degs and held for 10 minutes, when I pull the blade out and put it in the quench oil (parks 50) it flared up big. Now this wasn't just a 6 inch flare it was like a 3 ft high flare and it wouldn't go out. I threw the knife out the shop door before I burned the shop down and when it hit the ground the cement came off and continued to burn on the ground.
My question is, has anybody else had this problem and any ideas what went wrong?

Thanks Jim.
 

Kevin R. Cashen

Super Moderator
Hi Guy's. I recently changed my quench oil from canola oil to Parks 50. My first knife to quench in the Parks was a big bowie made of 1075. I wanted to put a hamon on this knife so I put Rutland furnace cement on it and went to heat treating it. I have a digital oven and heated the blade to 1525 degs and held for 10 minutes, when I pull the blade out and put it in the quench oil (parks 50) it flared up big. Now this wasn't just a 6 inch flare it was like a 3 ft high flare and it wouldn't go out. I threw the knife out the shop door before I burned the shop down and when it hit the ground the cement came off and continued to burn on the ground.
My question is, has anybody else had this problem and any ideas what went wrong?

Thanks Jim.
Two things I would immediately look at:

1. 1525F is too high for 1075 and especially for hamon work. 1475F or less would be better especially if you are soaking.
2. How much oil volume was there for the work? You need to be well below the surface of the oil with any part that could be hot.

You can get away with a vertical tank with the same amount of oil better than you can with a horizontal. The clay adds A LOT of thermal mass to the quench. With a bare blade I normally go for a 7-8 count for 400F but with clay it needs at least 10 or 11; but until you get the hang of it I would forgo the marquenching techniques. The thicker the clay the more heat it will hold and the more pronounced the problem.

Keep a cover handy for the tank in case this happens in the future. The safest way to deal with the problem is to just cover the quench tank and deprive the fire of O2, but the better way is to avoid flashing it at all. Another common cause for this problem is heating the blade while holding it with tongs, allowing the tongs to get hot enough to ignite the vapors since they will be at or above the surface. The oil does not burn, only the vapors mixed in the necessary ratio with O2 will burn, so it is at the surface and above where the problems occur. This is why I cannot tell people enough to not edge quench in a good quench oil, just get canola or some other alternative if you must use that method. Of course the first concern is your own safety, but the fire will quickly ruin your oil as well, and you no doubt have a significant amount of cash setting there.


I am confident in saying that I have been using Parks #50 longer than the vast majority of knifemakers out there, with the exception of Dan Maragni who introduced me to it so many years ago that I cannot remember, and I have yet to accidently flash it and I have done countless quenches of every kind both at home and at demos across the country. I have made some smoke with clayed blades but have yet to flash it. I know how it can be easily done but I also know how it can be avoided.
 
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Jim Coffee

Well-Known Member
Wow thanks Kevin. That's exactly what happened. It flashed when I pulled the blade out. I do have a vertical tank and after reading your post I now realize I didn't leave the blade in the oil long enough. Thanks.
 

Josh Dabney

Moderator
Jim,

I would add That although I use Satanite the clay seems to soak up the oil during the quench and make an extra spectacular flare up if she goes off. I do 10 seconds in the oil and agitating back and forth (horizontal tank) which all but eliminates any flare-up. I'll typically have only a light wispy smoke coming off the blade out of the quench.

ALWAYS be ready for that flare up though ! If I come out of the oil and it bursts into flames I go right back in fully submerged like Kevin suggests for an additional 3 seconds.

-Josh
 

Jim Coffee

Well-Known Member
Thanks Josh, Kevin. I reheat treated the blade and this time all went well. This is a hidden tang knife and i know now why it happened the first time around. Being a hidden tang knife I left the tang really long and it wasn't submerged in the oil and I believe that is what caused the flare up. This time I cut a little bit of the tang off and made sure it was completely submerged in the quench oil and I left it submerged longer then normal, all went well and no flare up just the little bit of smoke coming up off the oil. Big lesson learned here, that was the worst flare up I have ever had and things could of went real bad quick with that one.
 
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