A gentler quenchant

[evfreek]

Hi Bruce. Thanks for that tip on the light sheen. It worked. I gave the oil,water quench a try with about a 1/16" layer of oil. No fire, but stench and mess. The scale did not blast off leaving a silvery finish as it did for the plain water quench. The steel was harder than with the diaper quench, but slightly softer than plain water. A file would scratch but not cut. So still pretty hard. Quenching time was comparable to the diaper quench.

Lecithin might work. It is more of a surfactant and viscosity modifier than a builder. It may be good in combination with food starches to help them blend with water. But, I am staying away from these because of the prep requirement (starches don't really thicken unless they are cooked) and the microbial degradation, which can also lead to stench. I just found a reference by Houghton on sodium polyacrylate quenchants. Less film formation during the vapor blanket phase, and more convection suppression during the convective phase. Exactly what is needed for crack sensitive steels. They don't seem to sell small quantities of the polyacrylate to backyard blacksmiths. So, back to the diapers.

One polymer that is very visibly absent from the literature is the polysulfonates such as ammonium laureth sulfate. These are very inexpensive. Cheap shampoo can be had for $1 per bottle at the dollar store. These concoctions have very high viscosity, but the problem is uncontrollable foaming . Foam suppression is possible with ionic salts and small amounts of oil to form an emulsion. This could be a more friendly version of Bruce's oil quench. Animal/vegetable fats + laureth sulfate + salt may make an interesting biodegradable combination polymer oil quenchant with similar performance.

Bob, the reason why the brine is a more rapid quench is that the salt crystals that form with boiling destabilize the vapor film by producing nucleation sites. If you try it in a glass bottle while looking closely, you will see exactly what they are talking about.

[ApprenticeMan]

Brine quench is SCARY ! I felt like the whole bottle was gonna explode in my face, or the blade would!

[BobStrawn]

ammonium laureth sulfate and sodium laurel sulphate That is coconut or palm soap. Added to just about every soap mix because it will foam at low temperature.

Bob

[Joseff]

Expense aside, you really should try olive oil, even just once. Its a little less volitile than petroleum, and smells a lot better.
Joseff

[teknition]

Originally Posted by evfreek

and 20 or so grams of baby waste product. It is not even slightly tinged yellow, but I try not to touch it.

I think I will stick to quench oil

[evfreek]

Hi Joseff. It looks like olive oil would be a pretty good quenchant, except for the price. There was an article yesterday in the food section of the paper in the Food 101 section by Robert Wolke, professor emeritus of chemistry from the University of Pittsburgh. It talked about the smoke point of food oils, saying this is the point at which the oils degrade and release toxic chemicals. Olive oil, as long as it is the clear extra refined stuff (light) is pretty good. But not the deep colored extra virgin oilve oil.

Here are the numbers: canola 400F, cott 420, sunflower 440, corn 450, peanut 450, extra light olive 468, saf 510. I am not quite sure of these numbers since my notes were scrawled down, but the point of the article was that olive oil was OK for deep frying if you use the light. He went on to say that oils which have been taken up to their smoke point are not really edible and should be discarded.

Hi Tek. The baby waste product is not really all that bad. At 2% or so by weight, it is not even offensive. Also, it is safe to dump this on your lawn. Our county has laws against grey water (bath water containing skin particles). This cannot be dumped on the lawn due to the risk of generating airborne disease containing particles. Olive oil is also safe to dump on your lawn, since it is biodegradable, and the bugs will eat it up fast.

If you don't like baby waste product, you can bypass the baby. Mega packs of diapers from Costco cost about 20 cents per piece. A single diaper should be enough to make about 10 liters of quenchant. If you buy small packs at the local grocery, they are about 50 cents each. I am cheap and go to the local baby. These are free. Do not select the ones with solid waste product. Not only are they very offensive, they are actually dangerous, from a pathogenic standpoint.

[mark stephen]

Use a low temp. salt set up.Its pretty inexspensive and if you take the time to find out what your doing ,reliable.You can get the salts from Brownells that they sell as a blueing salts .Id stay away from anything that involves water.

[Rravan]

just wandering but would the hardness of the water make a difference in a quench?

[Tyler Murch]

Originally Posted by Rravan

just wandering but would the hardness of the water make a difference in a quench?

Yes. Tap water is usually no good. Don't get me wrong, I'll use tap water to quench a center punch or a cold chisel, but I would not use it for something like an ax or hammer. Use distilled water or rain water.

[Bentiron1946]

Back in the 70's I had acquaintance with a knife make that got blood from a small packing house to quench his blades. Was he full of bull in saying it was the best thing?