I may have stumbled across another poor mans substitute for extremely expensive metal marking.
In the past I have successfully used mustard to mark a knife blade
but it wasn’t any good on other metals I tried. Others have used moly lube with some success. I haven’t tried that myself.
So without further ado may I introduce Imperial Stove Polish Paste:
While the mustard didn’t cut the mustard on a piece of flat steel bar from the local hardware store here is the result using stove polish and only one application.
Now the marking doesn’t come out as dark as I would like but it is quite durable. On an old saw blade (bottom pic) I ran it 3 times with an application of stove polish between each run. I tried furiously to rub it off using Gojo hand cleaner which contains pumice and it won’t rub off.
I didn’t like the result I got on a piece of aluminum. I was able to wipe that off.
Oh the stove polish is cheap to buy too.