Join Date: Dec 2004
Location: Little House on the Prairie
Apologies for jumping in here, but please do not use HCl. Others may have a better experience than I have, but I think HCl is dangerous to use on weapons. Hydrochloric acid (a.k.a. muriatic acid) in those concentrations is very corrosive and will etch carbon steel darkly. I have had no success with trying to bring out patterns consistently with more dilute solutions of HCl.
Vinegar is an excellent etchant but may take some time depending on the amount of acetic acid present. Vinegar's acidity will deteriorate with age as the acetic acid is converted to other compounds.