Originally Posted by Jean
I know that it is used Alan but I don't understand how it works as both products are basically stable and inert
However I would propose the following chemical raction chain (just my assumption, no guarantee whatsoever): the salt (NaCl) may slightly react with the metal and produce ferric or ferrous chloride (Fe Cl3 or FeCl2, highly reactive and slightly acidic) and the sulphur may react with it and produce black iron sulphide (FeS) giving the "warangan" effect on the blade.
Yes I have attempted a stain using salt, rice water (i.e. the water that becomes cloudy after you rinse and soak rice in it) and sulphur, based off some info in previous posts on this forum.
Brushed it into a blade, covered it in cling/saran wrap. In a day it turned as black as squid ink. I freaked out after a bout a day or two thinking it would damage the blade, but it looked promising. I think had I left it, it would have done a better job.
Jean, what do you think the role of rice water (effectively starch) is in this method?