Made from Herter's original formula for that professional finish on soldered double barrels that cannot be hot blued. Also great for the occasional job when firing-up the tanks is just too much work. Not for stainless steel. Notes:Instructions:Degrease parts thoroughly Boil parts in distilled water until hot Remove parts and swab on Belgian Blue Boil until hot Remove parts and card off with damp steel wool (0000) Repeat steps 2-5 until desired blue is obtained Boil parts in clean water for 45 minutes Remove parts from boiling water and place in oil