I'm just sayin.......here's the method I use to harden a frizzen: First, I use an oxy-acetylene torch as a heat source, and I adjust it to burn a carbon flame. I hold the frizzen with a piece of welding rod through the screw hole and heat only the face of the frizzen, not the foot. I heat the part to a bright cherry red/orange color watching the surface until I see a wet or waxy appearance on the metal surface. I hold it at that temp for a couple of minutes. Then, I quickly immerse the frizzen in a special quenching oil purchased from a commercial heat treating supplier, moving it around to quickly cool the part until it is cool enough to hold in hand. I clean off the oil and temper in an oven at 375 degees F. for one hour. That is the method I and all of my assemblers use in hardening the frizzens on our assembled locks. That works for us. I'm not a metalurgist, have had no training, have not read any manuals, I just know what works for me to make a frizzen spark.
If you need to harden one of Stan's frizzens, by all means, follow his directions and dunk the part in water.
If you need to reharden a frizzen on a lock I assembled, send it back to me and let me do it. If you're determined to do it yourself, please use the method I described above. Or, use your own method, and I'll be glad to sell you a new frizzen if yours fails.
I'm just sayin................