I mainly use potassium nitrate salts for spring tempering or to blue small parts like screws. I never tried it on larger items such as steel grip caps or trigger guards because I have read that it isn't a very durable bluing process for parts subject to wear. I'm curious to hear if anyone has personal experience to share on durability. I am intrigued by the higher temp charcoal process such as that used by Colt or the Carbonia process used by Smith & Wesson. Obviously, those processes were beautiful and held up well. We had a good discussion about this a few years ago:
https://doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=574458&page=1Hi Keith
Sorry for the delay in replying, I've been playing around with both methods over the summer and discovered this, that if I take a soft wire wheel used for carding, that the wheel will remove the heat blued finish but not the charcoal blued one. In fact the charcoal blued finish looks better after carding.
Fred
