Quenching liquid. (Beginner question)

K

Karoo

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Jan 26, 2017
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15
Hello All
I am a novice knife-maker with a few under my belt.
I understand that specialized quenching oil is the best to use, but early research said that if you do not have this, then canola or peanut oil or, if necessary, used motor oil.
Now, I live in a rural area and have no access to any of this besides used motor oil and sunflower cooking oil.
Recent information has said not to use motor oil, so what advice do you give? Used motor oil or sunflower oil? At this stage I am looking only for strength and reliability. Aesthetics will come in time.
Thanks
 
I’m not sure but look into mineral oil or transformer oil. I think mineral oil is the main ingredient in most quench oils. Transformer oils are made to take heat out of things.

Hoss
 
Motor oil is a poor choice as it contains chemicals you don't want in your body. Quenching oils have different rates of removing heat from the steel. If you use simple oils use simple steels to match.
 
One place to find oil in rural areas is from veterinarians - the have vet grade mineral oil. This is also available from farm suppliers.

Sunflower oil will go rancid.
Peanut oil, canola oil (rapeseed oil) and even corn oil will work when nothing else is around.

Ok, as to motor oil.
It will work for any medium quench rate steel, but the vapors given off in quenching are not good to breathe. Transmission fluid works, but is the same concerning vapors. I have read of rural smith using hydraulic fluid, but don't have any first hand knowledge of this. I would guess that it works fine.

The steels to use for less than perfect quenchants, are those with less than 85 points of carbon (.85% or less). 5160, 1080,1084, 1075 all work. O-1 and L-6 also work in medium oil.

Depending on the steel used and your skill, brine can be used. Use a brine of about 8% to 12% salt by weight. Cracking is more likely with brine. Use an interrupted quench where you stick the blade in for about three seconds, lift out for three seconds, and then put back in to cool the rest of the way. Just be aware that blades may warp or crack in a brine quench.
 
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https://www.researchgate.net/public...e_and_Quenching_Performance_of_Vegetable_Oils

Not sure if you can see the paper unless you have an account there at researchgate. But the upshot is that at 60C, the vegetable oils they tested basically all had the same cooling rate. Canola is the veggie oil of choice because of two reasons: 1) it's very cheap, and 2) it's more stable than the other vegetable oils tested. But I bet you should get relatively similar performance quenching with the sunflower oil. You might not be able to use it for as many blades before it breaks down to the point it isn't as good a quenchant any more.
 
I agree that sunflower would work for a few quenches, but tossing away a gallon of oil every week or so may be expensive. The issue is sunflower ranges from, 50% to 90% oleic acid. Canola is low acid (CANadian Oil Low Acid).

These are some common oils in the order of usability:
Grapeseed oil
Avocado oil
peanut oil
canola oil
olive oil
corn oil
 
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Stacy E. Apelt - Bladesmith said:
I agree that sunflower would work for a few quenches, but tossing away a gallon of oil every week or so may be expensive. The issue is sunflower ranges from, 50% to 90% oleic acid. Canola is low acid (CANadian Oil Low Acid).

These are some common oils in the order of usability:
Grapeseed oil
Avocado oil
peanut oil
canola oil
olive oil
corn oil
Click to expand...

Didn’t know that. I always thought canola oil was from the canola crop, aka rapeseed.
 
DevinT said:
I’m not sure but look into mineral oil or transformer oil. I think mineral oil is the main ingredient in most quench oils. Transformer oils are made to take heat out of things.

Hoss
Click to expand...
I’ve got a knifemaker buddy who was a lineman for years. He swears by transformer oil. I know it works great on 52100..
 
DevinT said:
Would the newer ones be a good quench oil?

Hoss
Click to expand...
The oil used now days is just mineral oil, IIRC. I imagine it works, though something like Parks 50 probably is not going to be much more expensive.
 
Yes, "Transformer Oil" is usually light mineral oil with some fire retardant added. Veterinary oil is just a purer grade of light mineral oil. The PBC oil mixes have been banned almost 50 years ago.
 
I think there are still a bunch of the PCB transformers out there though. The way I remember the power guys telling me when I built my house the ones without PCB have a blue circle on the transformer.
( when building my house the guy running trackhoe knocked a pole down and it leaked oil, while the power company was getting the oil up the hydraulic hose on the truck broke and they had to get up all that oil too , they spent like 8 hours just recovering the oil that was on the ground)
So thanks to a fool on a trackhoe my transformer is PBC free :cool:
 
Spalted said:
I think there are still a bunch of the PCB transformers out there though. The way I remember the power guys telling me when I built my house the ones without PCB have a blue circle on the transformer.
( when building my house the guy running trackhoe knocked a pole down and it leaked oil, while the power company was getting the oil up the hydraulic hose on the truck broke and they had to get up all that oil too , they spent like 8 hours just recovering the oil that was on the ground)
So thanks to a fool on a trackhoe my transformer is PBC free :cool:
Click to expand...

As Stacy pointed out, the production of the oil has in fact been banned (at least in the US) since somewhere around the mid to late 70's. That said, there absolutely are still plenty of transformers full of PCB oil that are still in use, as it just wouldn't be feasible or cost effective to swap out (or reclaim and fill) 1000's upon 1000's of perfectly functional transformers, logistics of disposal notwithstanding.
That said, I imagine somebody's bound to have a few gallons of the stuff sitting out in a barn somewhere, which was the only reason I mentioned it, though I'm also sure the chances of it are also becoming increasingly slim.

Besides, depending on the oil, there are plenty of other things one might want to worry about, besides PCBs, anyhow. Personally, I'd just buy a couple gallons of Parks and call it a day.
 
Take this with an obvious caution. I heard of one maker using diesel oil as a fast quench oil. I would think there are obvious fire hazard concerns, but that maker said it was fine.
 
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