Olive Oil vs. Peanut Oil

A

artney_iv

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Apr 19, 2013
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I was talking to a gentleman in Scotland this morning that suggested using 180 degree C olive oil for a quench and dipping vertically. I'm trying to heat treat a long blade (you may remember the first attempt didn't go so well so this is round 2.) The whole piece is 22 inches long with a 14 inch blade.

My questions are:
Is there a real difference between olive oil and peanut oil when using them to quench?
If olive oil is better, where can I find it in say a 5 gallon quantity? I know I can get peanut oil rather easily.
Finally, for something like this, dip vertically or horizontally? Or is that just up to preference and the tools at hand?

Thanks to all.
 
I used olive oil for years with O-1 and had pretty good results, it is a very slow oil but O-1 was OK with that, if you are going to use something other than an engineered quenching oil for something like 1084, use canola heated to 130f. I use Parks 50 for most things now, but for my traveling workshops use canola so I don't have to worry about safegaurding my Parks

-Page
 
As for the Olive Oil, if you are looking to get quantity sizes, look into buying from a food supplier. I'm in the restaurant business and use a ton
of it a week. I buy mine from Sysco foods. If you have a GFS (Gordon Food Supply) in your area, they usually sell it by the gallon. It is open
to the public. Same for your Canola Oil. (cheaper than Lowes, etc for fryers)
 
Like Page I suggest canola oil. I use parks 50 now with the exception of 52100 which I get max hardness out of canola oil. My other steels get parks or brine if I am feeling adventurous.
 
I've wondered the same.

Is it a viscosity thing? I've got a bunch of olive oil for some reason, but not a lot of canola. Of course I'm going to just go buy the canola when it's time to ht my 1084, but still wondered.
 
I'm not sure what the steel is. It's out of an old circular saw blade is all I know. I've made several knives from them before and heat treated in motor oil with good results, but I know that's definitely not preferable and I'm looking to get an oil that's better suited for the task.
 
Canola is broadly used, studied (googley) and well-understood. If you use other food oils you're off in less-well-tested territory, and unknowns are not conducive to consistent results.

Yes, it is a viscosity thing, as I understand it. The super-heated oil needs to be able to move away from the blade quickly in order to keep the quench speed high enough. Cold oil keeps the hot pocket surrounding the blade. 130F canola seems to be the go-to standard for natural oil quench. Motor oil is terrible choice as the quench speed is unknown relative to other oils (and so many variants!), the flash point is much lower, and the fumes are poisonous.
 
Thanks for the advice and thanks Hankins for the link. I'll definitely look into picking some up.
 
You can pick up 5 gallons of canola oil from Costco fairly cheap - as mentioned above its sort of the go-to oil < actual quench oil
 
peanut oil works very similar to canola, withmaybe an even higher flash point. heated to 130-140F, I've had good results on 1084 with it.
180C = 356F, which is about where you'll be tempering at, not quenching.
 
I did canola with 15n20 and would get an as quenced hardness of 62. This is room temp oil with very vigorous agitation.
 
Please say the 180C was a typo. I wouldn't quench anything red hot in 350 degree oil unless the oil was specifically made for it.

62 sounds a little low for an as quenched hardness. Perhaps heating the oil is the answer?
 
It sounds like the Scottish chap was referring to marquenching. This is when you quench the hot blade in a media that is at just below the Ms. 180C would be about right for carbon steel.


It is a really bad idea to use any flammable oil as a media for marquenching....unless you have industrial equipment with nitrogen shielding and fire suppression.

Low temp salts are the normal media used for marquenching knives. Old methods like hot oil and molten lead are not used anymore by most folks for obvious safety reasons.

The normal quenchants are oils that are heated to around 130F, and some not heated at all ( Parks #50). Canola oil is an acceptable alternative for commercial oil in a pinch, but the real quench oil will last far longer and cost nearly the same.
 
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