Preventing / minimizing scale during heat treating?

[Tom B.]

Anyone have any tricks or best practices for minimizing scale during hardening?

I found this stuff (PBC anti scaling compound) from the makers of Cherry Red

I found this thread about DIY anti-scaling compounds on the Home Shop Machinist site.

[Signo]

You basically need to have a slighty reducing atmosphere instead of an oxidizing one.
What does it mean? That if you heat treat with a flame, the mixture need to be rich instead of lean. In this way, the combustion will consume all the oxigen, and there will be none to oxidize the metal.
If your kiln is electric, you may simply inject an inert gas inside the chamber to make the oxygen go away.
The product you cited work on this principle probably, seizing the oxygen from the atmosphere.

[losthelm]

I wonder if simply coating it in a layer of kiln wash would work providing a barrier between the steel and atmosphere.

The Water in the kiln wash would need to be baked off in a preheat but that should not be a problem.

[Tom B.]

Reading the thread I linked to above most of the stuff mentioned involves making a coating on the metals surface, either a dip or painted on coating.

[Halberds]

I used to use SS foil to wrap the parts in.
A piece of brown baper bag was placed inside to burn.

It works great on tools but I am not sure how well it works on armour.

http://www.mcmaster.com/#heat-treating-foil/=k39j2t

[Tom B.]

I used to use SS foil to wrap the parts in.
A piece of brown baper bag was placed inside to burn.

It works great on tools but I am not sure how well it works on armour.

http://www.mcmaster.com/#heat-treating-foil/=k39j2t

I know about the foil bag but this is not practical for most armour pieces.
Certainly could be used for small pieces of mail and gauntlets.