Before Our Gov't decided to Help Us, Nicholson file used to coat their freshly cut file blanks with "cyanide loaf" to prevent any loss of carbon during their very short heat treat at 1440F, water quench.
This depended upon potassium ferrocyanide to start things out, just like (I think) in Kasenit. The mixture was:
Potassium ferrocyanide, K4Fe(CN)6, mixed with flour and bone black, all boiled together in salt water.
As this is a fairly conservative group I will include the 16th century version:
Take Ox hoofs, and put them into an Oven to dry, that they may be powdered fine; mingle well one part of this with as much common Salt, beaten Glass, and Chimney-soot, and beat them together, and lay them up for your use in a wooden Vessel hanging in the smoak; for the salt will melt with any moisture of the place or Air. The powder being prepared, make your iron like to a file; then cut it chequerwise, and crossways, with a sharp edged tool: having made the iron tender and soft, as I said, then make an iron chest fit to lay up your files in, and put them into it, strewing on the powder by course, that they may be covered all over: then put on the cover, and lute well the chinks with clay and straw, that the smoak of the powder may not breath out; and then lay a heap of burning coals all over it, that it may be red-hot about an hour: when you think the powder to be burnt and consumed, take the chest out from the coals with iron pinchers, and plunge the files into very cold water, and so they will become extream hard. This is the usual temper for files; for we fear not if the files should be wrested by cold waters.
So if you have an ox around this might be a good way to go.
An excellent reason to pack harden new frizzens in something with charcoal, is that surface carbon burns out of that frizzen as it cools in the mould. The thing now needs to have that carbon restored, for us that means pack hardening.
It is the steel, and not the carbon, that burns as sparks from a frizzen. The word "frizzen" is related to "frizzle", meaning little curly chips. Like frizzy hair.