Ferric chloride 1 part
Alcohol 8 parts
Rainwater or de-ionised water 8 parts - all by weight.

Apply a thin coat with a dampened sponge. Heat work to 37 degrees C in a closed container with steam, (I use a plastic drain pipe connected to a wall paper steamer) until a thin rust forms. Boil in water for fifteen minutes, brush off loose oxide, repeat until the desired finish is obtained.

Ferric chloride is used for etching copper circuit boards, and may be bought on .