Birchwood Technologies (formerly Birchwood Casey Metal Finishes) is the chemical supplier of our Antique Black, Antique Brown, and Presto Black patinas for copper, brass, bronze, and steel. We have been manufacturing chemistry for sculptors, artists, and architects since 1948 and have a reputation for high quality and dependable patina solutions. https://www.birchwoodtechnologies.com/products/decorative-finishes/