The solution used can be the same for either color, although some solutions are considered best for one or the other methods. In both processes the solution is applied cold & allowed to rust. For the "Black" Browne the part with rust coat is subjected to boiling water or steam to do the conversion prior to carding. This not only converts the color but also makes carding easier as the excess rust is loosened leaving that which is to stay firmly attached. Boiling water does not hurt a solder joint, in fact the temperature of a hot salts bluing tank does not hurt the solder, the chemicals in the hot tank attack the solder, specifically the "Lye". It will also violently attack Aluminum.
