Painting on Zinc or on Galvanized Iron.
Painting on zinc or galvanized iron is facilitated by employing a mordant of 1 quart of chloride of copper, 1 of nitrate of copper, and 1 of sal-ammoniac, dissolved in 64 parts of water. To thin mixture add 1 part of commercial hydrochloric acid. This is brushed over the zinc, and dries a dull-grey colour in from twelve to twenty-four hours, paint adhering perfectly to the surface thus formed.