Thank you Stacy for reminding us of another common disconnect in communicating knifemaking methods, techniques and skills. I kind of call it the hammer-in syndrome, i.e. in less than a hours time a very highly skilled and experienced person demonstrates to a group of beginners what took them years of experience to be able to demonstrate it an hours time. These demonstrations often end with something like “…and that’s all there is to it!” without any emphasis on the fact that the demonstrator has been doing it for 20 years. Hammer-ins are great to dip ones toe in the water to see if this is going to be their thing but it is far from a swimming lesson that will allow you to dive in and swim without drowning, and the guys they like to get for hammer-ins will make it look deceptively easy.
I do use salt baths and controllers and that will account for being able to work O1/L6 for eight minutes after the interrupt, but I do practice the timed interrupted quench regularly with even coal forges. I just got my advance copy of 3 new ABS DVD's of my forging grinding and heat treating lectures at Troy Ohio and in heat treating I do a marquench using a coal forge and a clayed blade (a very rare demonstration from me)*. I feel safe mentiong the DVD's here because I don’t get a dime; all proceeds go to the ABS.
That being said, marquenching techniques are advanced methods of heat treating and people really do need to walk before they run, and it takes even more skill to pull it off just right without the specialized equipment. Particularly in this case where there are heavy smoking issues with the oil, it is really best to get everything hot under the surface and keep it there until it is cool. Then temper the blade normally and see if you can straighten any kinks by heating the spine with a torch while keeping the edge cold with a wet cloth or cerawool and pushing it straight.
*I really need to stress that applying clay to blades is not a standard part of heat treating and has been one of the greatest sources of miscommunication over the years. People using clay need to realize that unless the advice specifically mentions clay it is assumed that it is just steel being heated and quenched, and if you are using clay you need to mention this to the guy you are requesting advice from. For example, in that DVD I mentioned, you will see large volumes of smoke from the oil because that is what clay does, it takes up the oil like a sponge and holds heat to no end and thus produces 5 times the amount of smoke. I even get a brief flash at one point because my tongs are hot and the vapors are heavy, I never get flashing on bare blades and overheated tongs should be the only possible source for surface smoking if you are not doing an interrupt.
