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View Full Version : What is "vet-grade" mineral oil?



rob45
11-12-2010, 11:40 AM
Hello to all.

I am very inexperienced with the entire heat treating routine, but I am making an attempt to soak up everything I can both here and elsewhere.

In my attempt to learn more about the various steels and quench mediums, I have read about "vet-grade" mineral oil in several of the posts here. I do not know what that means.

I have an appreciation for fine kitchen cutlery and accessories. In the past (and sometimes still as gifts, etc.), I have made several cutting boards. Over time, this has resulted in the acquisition of several gallons of "food grade" mineral oil. For consistency, this oil has been purchased from only one source, and all of it is the lightest viscosity they offer.

The manufacturer (STE Oil Company in San Marcos, TX) has a website. Searching there, they have an application chart to help select the proper oil. It states that my oil (70FG) is suitable for "veterinary preparations".

So are they talking about the same thing, or am I prematurely drawing conclusions? It sure would make my day to know that I already have a supply of one of the quench mediums I would like to try out.

Thanks,
Robert

jkf96a
11-12-2010, 03:03 PM
From what I understand, vet grade is essentially the same as food grade. It is sold at feed/farm stores as an large animal laxative. Unfortunately, there doesn't seem to be a standard viscosity, which is one of the key factors for quenching effectiveness. I've heard quench speeds in the 14 second range, but have no verifiable data or source. At least one "famous" bladesmith uses it exclusively, for steels to which it is well suited.

Here's a thorough discussion of the subject, with a bunch of other links included.
http://www.bladeforums.com/forums/showthread.php?t=785645&highlight=vet+grade

rob45
11-17-2010, 04:21 PM
Thanks, Jason.

That link provided a lot of info. As usual, an answer for one question leads to another.

I contacted the manufacturer, and they confirmed your statement on the viscosity- there is no set standard.

At least all of what I do have is the same, so it's a baseline for experimentation.

Thanks,
Robert

Mike Krall
11-20-2010, 09:21 PM
Robert,

Have you looked into commercial quench oils... they are designed specifically to do the job I think you are looking to do. That's not true of mineral oil.

Mike

rob45
11-22-2010, 09:59 AM
Robert,

Have you looked into commercial quench oils... they are designed specifically to do the job I think you are looking to do. That's not true of mineral oil.

Mike

Mike,

The only items I've made which required hardening are some homemade chisels and a metal scraper. These were made from old, dull files.
A few of the chisels made it fine through a hot water quench, but some others cracked (that's a rather heartbreaking sound!). I made replacements for the cracked items and then used old motor oil.
The tools work great. They hold edge longer than items bought at the store, and are more specifically shaped for my application (the reason I made them).
But the motor oil quench was "unpleasant". I thought perhaps the mineral oil would be a cleaner process. I have over ten gallons of the stuff sitting unused, as I no longer do near the amount of woodcrafts I used to.

With that said, I have yet to forge and heat treat a blade. I have done some forge work, but that has been mainly decorative household items and the few tools mentioned above, and all have been made from "mystery steels".
All knives made to this point have been produced using stock removal methods, and then sent out for heat treating. But I need to learn more and get some experience in forging blades; belts can get expensive, and my time gets more limited every day.

So this is definitely new territory for me.
I read various threads concerning "7-second oils", "11-second oils", etc., and get lost in the vacuum because I have no idea what that means.
I need to research what has historically performed best for the steels I wish to use, and start there I guess.

BTW, sorry it took so long for the reply; at times my availability on the computer is limited.

Thanks,
Robert

Mike Krall
11-22-2010, 09:39 PM
Robert,

I sure don't need an apology... =]

I can understand you not wanting to get into a large quench oil expenditure, given the amount of use you would put it to. Just so I've said it, I'd buy commercial quench oil before I bought a whole lot of things for making knives and other cutting tools... like a kiln, grinder, full-on forge (as opposed to coffee can or "two brick"), and the list goes on and on. A person can work around a lot of things making a knife but a commercial quench oil gives a person so much of an edge it's astounding. Yeah, even quench oil can be worked around.

If I was messing with files for stock (high carbon, simple steels, like 10xx and W1/W2), I'd look into canola oil or a brine quench. Canola oil, by nature has a cooling curve that is very similar to fast-type quench oils... even to the extent of the curve slowing below the perlite nose (as commercial quench oils do and as just about all the other substitute quench oils do not). I think a person ought to be able to do interrupted quenches with brine. I don't know how to begin to approach the process, though. I know from reading that brine is not as hard on steel as water because the salt doesn't let a lot of air along the surface of the steel (boiling phase of quench). It is actually a faster quench than water so, in theory, a person could miss the perlite nose in very little time, then let the blade air cool into martensite. Maybe that would significantly reduce the incidence of "tink".

I'm not sure even low viscosity mineral oil is fast enough for the steel you use and I'd guess you were going to deal with a similar amount of smoke, if not the same nastiness, as motor oil.

The speed of quench oil seems to me to be commonly discussed roughly in 7-sec., 11-sec., 28-sec., etc. terminology. The speed in seconds is not all of the story and many manufacturers list the speed-in-seconds as a range. It seems to me to be easier to find companies making (or businesses using) quench oils and ask the tech. department which oil is suitable for a specific steel... if a particular oil is very suitable for a particular steel, in a particular form, it doesn't make any difference what it's seconds-number, or range, is.

Here is an example of that... Houghto-quench "G" is a medium speed oil (the same oil that is sold by Brownell's and labeled as "Tough Quench", by the way), suitable for steels like L6 and O1, etc. Scott McKenzie is Houghton's metallurgist and quenchant specialist. Scott says "G" will fully quench a 1/4" thick piece of "fast" steel (10xx, W1/W2). H-q "G" is not a 7-9 second oil and it's speed in seconds is irrelevant to it's function in this specific instance. It's the "fully quenched" that is relevant. So if "G" is an 11 second oil, will other 11 second oils fully quench 1/4" W1? Kevin Cashen has said Park AAA (nearly identical to "G") will make a natural hamon at the very top edge of a 1/4" spine... so no. The kicker is, Park AAA is actually a thin-hair faster than H-q "G", if both are new (AAA slows a little as it is used extensively and ends up on the other side of "G").

In the end, as Kevin Cashen and others have said a number of times, the slowest oil (cooling curve) that will "fully quench" a particular steel is the ideal.

Mike

Kevin R. Cashen
11-23-2010, 08:11 AM
Robert,

I sure don't need an apology... =]

I can understand you not wanting to get into a large quench oil expenditure, given the amount of use you would put it to. Just so I've said it, I'd buy commercial quench oil before I bought a whole lot of things for making knives and other cutting tools... like a kiln, grinder, full-on forge (as opposed to coffee can or "two brick"), and the list goes on and on. A person can work around a lot of things making a knife but a commercial quench oil gives a person so much of an edge it's astounding...

From all of my personal experience and observation of the struggles of others, for some time I have said that if there were two things that a would be knifemaker could get to give them the best advantage right from the start it would be a fresh bar of steel of a known chemistry and a well formulated quench oil to match that steel. I understand that Robert isnít plunging in that direction right now but the guys who are often get so caught up what may be best for the steel vs. what is best for their wallet that they ignore what may be best for themselves.

Short of working side by side with a mastersmith it can take many years to work out many of the processes in making a good blade, that can get stretched out to decades if the rules are always changing on you without your knowledge. Obviously mystery steels will do this to you, but there are indeed liquids that may be faster or cheaper than engineered quench oil, but they do not provide the reliable consistency of a product designed to quench the 500th time the same as it did the first. Eliminating just one variable in such a critical area frees one up to explore countless other critical factors of the learning curve.

It sounds like Robert will be pressing his quenchant mush less than a more prolific knifemaker so an alternative may get him by. The motor oil really isnít an alternative for any kind of quenching for many reasons, but a very light mineral oil may be. By light I take us back to the viscosity topic, it would have to be the runniest mineral oil you could get, close to WD-40 in runny. All the fast quench oils I have worked with did not feel at all like a lubricant between your fingers but really watery.

Considering the light use it would see I may even suggest a very light vegetable based oil for Robert, before risking the wrong mineral or petroleum based oil. Canola oil or a very light corn oil may work, lowest on my list would be peanut oil which despite its popularity I have found to be less than satisfactory for our purposes.

But in the end I still stand by my position that if I had to suggest two things that would give a new maker the greatest advantage in learning our craft it would be a good known steel and a good quenching oil. After this I would also recommend a library card, and a Bic lighter for any magazine articles they already began reading.:3: