Glenn

Quenching in old motor oil

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There have been many comments and options on which oil is best for quenching. Most say to stay away from used motor oil because of the contaminants picked up (presumably) from the wear and tear of the engine parts.

Please keep this subject on used motor oils from vehicles.

Does anyone have any hard evidence (references, URLs, test results, etc please) as to the contaminants contained in the oil and why they should be avoided? Just how contaminated is the oil? What happens to the contaminants when the hot steel is quenched, where do they go? If we can produce the evidence, we can eliminate the myth and opinion, and find the facts.

The next question would be why not eliminate the contaminants and just use NEW motor oil instead?

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One big trouble is gasoline contamination. You would not want to quench and have a fire that would be extremely difficult to extinguish.

I'm sure many people have employed used motor oil with success but it's probably not the best choice.

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Having used old drained off engine oil I have found it to severely blacken the finish on carving chisel blades I have made. There are heavy carbon deposits which can be difficult to remove and a tendency for the oil to flash ignite quite readily

I now use new oil in the tank and have far less problems.

When using old used engine oil, the actual viscosity and from what use it came from is not always known, I find a clean new transmission fluid or flushing oil is succesful and can be used many times.

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According to Alabama's Project R.O.S.E. (recycled oil saves energy) website,
Used Motor Oil: A Problem with a Solution,......."While an automobile is running,the motor oil collects dirt,heavy metal(lead,cadmium,zinc and barium) and other things.

I also looked at some info from the American Petroleun Institute (API).

I never quite figured out whether the so-called "contaminants" are supposed to come from the engine, the gasoline, or the additives that are put in the oil itself.

The informatiion on this subject is somewhat contradictory.

On the one hand,used motor oil is considered toxic(a hazardous waste),

yet ,on the other hand,it can be re-refined into safe 'new' engine oil.....or it can even be burned in a 'properly designed' furnace to heat an office building.....or your home!

After my web surfing on this subject ,that's all I came up with.

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what do you guy's think of used veggie oil? my father and I do bio-deisel, and are going to run our cars on straight grease here pretty soon.. so we have a few thousand gallons of the stuff sitting around.
It has some fine food particals in it, but they can be filtered out.. and I've quenched a blade in it once or twice.

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I made do with used motor oil for quite a while, then just said the heck with it and bought 10 gallons of peanot oil to use for quenching. Much better to use with less toxic smoke and smell. Haven't seen any difference in the effect or efficiency of the quench. But can do it inside now.

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Dad told me way back when I was a kid playing with grinding out knives from old files, " If it stinks and makes your eyes burn , then it probably isn't a good idea." Took him to heart.
Finnr

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If you wish to get a better idea of what is in used motor oil, send a sample to an oil analysis center. For example, many heavy truck fleets during oil changes will send samples away to companies such as Caterpillar for aid in engine analysis. By examining the oil and its contaminants, you can clearly see what is in used oil. The guys are right, you will find heavy metals, sulphur and such. You definitely do not want fumes from any of this stuff in your lungs or on your skin!
I say use whatever quench for your iron that you wish; just be consistent and don't use waste oil.

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Lots of the heavy metals come from the bearings that wear in an engine. The main bearings in an engine are generally a babbit material.

Recyceled Fry Oil is a common quenchant.

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On page 21 of Basic Blacksmithing (Davies and Heer) they suggest a thin mixture of earth and water as a suitable alternative to oil for quenching. Never tried this, but it would certianly not be flammable, environmentally friendly and free (apart from the water perhaps)...

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My mother was a stonemason back in the 40's and they made all their own tools. The men peed in a bucket and tools were quenched in neat urine. I know this is unrelated to the original topic, but anyone had any experience of this? 

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I get that you use what you have, im all for that. But why didnt they just use water?!?! Its literally the most cost free thing on this planet and is far less.... disgusting. 

 

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Well I guess they thought the minerals in urine did something to the steel maybe. My mother was trained by her father back in the late 1940's, who in turn had been trained as a stonemason just after the First World War - I guess people were still doing things as they had done for centuries. This was in central Europe and no doubt before the advent of cheaply available oil, so people generally would have quenched in water.  Sounds disgusting now, but 100 years ago sanitation was almost non existent in their small village, so collecting urine to quench chisels was probably thought quite normal. Just wondered if anyone else had come across this, whether there was merit in it or just another ancient activity like blood letting and leeches that have no scientific basis.

I'm not planning on following the family tradition by the way! Vegetable oil seems a xxxx site easier.

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Well urine is a weak brine, so in theory, it should quench slightly faster than water by itself. But i know Thomas Powers has a story about quenching in urine. 

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Urine is mostly water and dissolved urea and uric acid salts.

Those salts could readily be substituted by table salt. That is sodium chloride. There is nothing magical about the two chemicals, nor its solution in water.

Every summer, at summer camp, one young fellow would invariably try to put out a campfire by peeing on it. The results were an odor that was vile.

The nitrogen atoms, in urea and uric acid, readily formed volatile compounds, with the heat, to make a delightful pong.

NOT.

Stale urine also forms ammonia, and that dissolved ammonia cuts grease big time.

The Inuit, in Alaska and northern Canada used it to clean dishes' before super markets and Wall Mart arrived.

There are no mineral salts in urine, unless the pee-er is suffering from acute metal poisoning.

Enough trivia concerning pee.

SLAG.

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Well I guess they thought the minerals in urine did something to the steel maybe. My mother was trained by her father back in the late 1940's, who in turn had been trained as a stonemason just after the First World War - I guess people were still doing things as they had done for centuries. This was in central Europe and no doubt before the advent of cheaply available oil, so people generally would have quenched in water.  Sounds disgusting now, but 100 years ago sanitation was almost non existent in their small village, so collecting urine to quench chisels was probably thought quite normal. Just wondered if anyone else had come across this, whether there was merit in it or just another ancient activity like blood letting and leeches that have no scientific basis.

I'm not planning on following the family tradition by the way! Vegetable oil seems a bit easier.

Had to edit this as the moderator warned me about the use of the word da*n - a cultural difference I think since it is just a commonly used word in the UK with no offence inferred.  Apologies to anyone who was offended.  Anyway, end of subject.

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Many "special recipes" for quenchants have been used over the centuries; "Sources for the History of the Science of Steel"  C.S.Smith, has a listing from the renaissance each one promising to make your steel harder and whiter---including radish juice, cockroach water, snail water, etc.  In general they break down to the basic Oil, Water, Brine categories---blood can be considered a weak brine for instance. So yes they often have some value; but sea water or a stronger brine would have worked *better*!  (I've quenched in stale urine from a vat dyed indigo  project my wife did; worked ok and had such an amusing smell when hot steel is plunged into it!)

Remember  too that modern steels are often MUCH MORE FINICKY about their quenching than the old stuff!

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So.......what is a good medium for quenching.  Personally I wouldn't use old motor oil the viscosity will not be uniform and contain unknown contaminates.  I'm not interested in brine infused fluid, just a good, dependable quenching agent. 

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Well it would depend on what alloy you need to quench; some alloys you quench in oil and they won't harden. Some alloy you quench in oil and they may crack or shatter.

Perhaps reading the heat treating stickies under knifemaking would help;  or doing a good web search (the forum search function is not so good; I use google to search and add iforgeiron.com as one of the search terms).

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Most sources cite the following contaminants: leadcadmiumchromiumarsenicdioxinsbenzene and polycyclic aromatics.

No one mentions water, I suppose because it is assumed to be harmless, however since motor oil is higroscopic, the water content would play a role in the quenching properties, that is, the more water the faster the quenching if compared to proper quenching oil ... or French Wine :)

Metallic contaminants will stay in the oil when used for quenching but organic contamination can become volatile when hot steel is submerged in it making it a hazard.

Ships use expensive centrifuges to clean fuel and oil but home made centrifuge can be put together with little money and process a lot of oil if built for continuous use. Check YouTube for ideas, or see "simplecentrifuge.com"

If it is worth your while doing it or just buy new motor oil when it is cheap, is your choice. The centrifuge can also be used to clean vegetable oil to make biodiesel, or to clean contaminated diesel.

 

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On 11/12/2017 at 12:42 PM, SLAG said:

e also forms ammonia, and that dissolved ammonia cuts grease big time.

The Inuit, in Alaska and northern Canada used it to clean dishes' before super markets and Wall Mart arrived.

There are no mineral salts in urine, unless the pee-er is suffering from acute metal poisoning.

Enough trivia concerning pee.

SLAG.

The romans used it to whiten their teeth.. 

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