To all:
As I've said before, before planning on getting a frizzen re-hardened its a very good idea to find out if it even needs to be hardened.
This is easy to do if one has a metal cutting file of any kind.
Try filing on the face of the frizzen which the flint will strike.
If the file bites into the metal and starts to remove filings, the frizzen needs to be hardened.
If the file doesn't bite into the metal and it just leaves a slightly shiny or polished look or leaves no evidence of its removing metal at all, the frizzen hardness is not the problem.
The problem is with something else like a dull flint or the flint striking the frizzen at the wrong angle.
Truth be known, the sparks are caused by the flint cutting off thin slivers of steel.
This cutting action heats the metal at the point of the cut to well over 2000°F which causes the carbon in the steel to ignite.
This sparking will happen even if the frizzen is dead soft.
If you don't believe me, get a piece of medium or high carbon steel that has not been hardened.
Take it to a grinder and touch the spinning wheel with the steel. A shower of white hot sparks will instantly come flying off of the steel.
The hardening only keeps the flint from digging into the steel too deeply and wearing away the surface too rapidly.
There was a time, many years ago, when the frizzens were made out of a low carbon steel.
The low carbon content caused the steel slivers to fail to ignite so few sparks were created.
To fix this, the low carbon frizzens were case hardened, a process where carbon is introduced into the surface of the soft steel.
The carburized parts were then heat treated to harden the high carbon steel surface layer.
Worn case hardened steel will eventually get its high carbon steel layer worn off and the only way to repair it is to case harden it again or to install a thin piece of thru hardened steel.
All of the flintlock frizzens that I know of that were made recently are made from a alloy steel which hardens completely thru the part.
Because the entire frizzen is hard all the way thru it, the battery on these alloy frizzens do not wear out until the entire part becomes worn thru. (Something that takes thousands of shots).
Keep all of this in mind when someone tells you your frizzen is too soft.