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.
