Quote Originally Posted by keith66 View Post
Yes, in Angiers book there are many recipies, Ammonium Chloride, Mercuric Chloride, Ferric chloride are all common ingredients, they promote rusting with a vengeance, Other ingredients can & have been used. Its the old slow rusting process. Not worth making your own as some of the chemicals will be hard to obtain. Ferric chloride was often used in schools for PCB etching, We had a big tub of the granules where i used to work, should have had some!
Ammonium Chloride is readily available and so it Copper Sulphate which is all I used to re-brown my gun barrel.

I know what you mean about some chemicals being hard or impossible to obtain. Years ago you could by dilute Hydrochloric acid from the chemist that was strong enough for etching. But I doubt you would manage to get any these days.