What do you use for heat treatment?

Duncan,

This American has little respect for the American Tubal Cain.

Check Clickspring's videos for his method of hardening using borax to eliminate scaling. There used to be anti-scale products available in small lots. MSC lists this:

**LINK**

That could be quite dangerous especially if the single droplet wasn't injected, even then it would surely cause an explosion, perhaps the combustion gases are helpful in preventing scale ?

Emgee

Dan explains it here at 22:30-

No mention of leak hazards but you get a nice flame shooting out of it when you open the door. Mind your eyebrows.

I use a product called ATP-641 from Ground Flat Stock in the UK. I believe it may be of US origin. Link below.

ATP-641 Anti Scaling

ATP-641 is a water based grey sludge that you dunk the object in and allow to dry in air. It is essential that you thoroughly clean and degrease the parts first as being water based the sludge 'runs back' from grease and does not cover the object as a result. It is also important to make sure the coating is thoroughly dry before putting the objects into the oven. The dry coating does chip easily so care is needed. Once the object is quenched, the grey sludge protective shell just crumbles away leaving a dull grey but clean surface on the object that is easy to polish up. Easy to use and very effective.

Reccomended. It doesn't like being frozen so beware keeping it in a cold workshop. Also good as a basis for the clay when hardening something like a japanese sword. Mainly because it 'sticks'. You probably won't find details of the mix that Japanese masters use - some combination of clay, sharpening stone slurry, charcoal etc... probably rat droppings in some. Bodging up your own is quite likely to result in something that falls off. I have had some success with fireclay.

Edited By jaCK Hobson on 18/12/2021 11:33:24

ATP-641 doesn't "wet" the surface of the (clean) steel all that well and I've found that adding a little drop of iso-propyl alcohol or meths to it helps a lot and provides better, more even coverage. Works for me anyway, although it's not in any of the instructions. Obviously let it dry before placing in the kiln.....

Clive

A simple point in the context of tempering DO NOT use engine oil, it will fume badly, cooking oil is better and a deep fat fryer will work. Good luck. Noel.

Still using paraffin blowlamp from the 1951 a Monitor,and a Berlyn 1965

Mick