How to Create Patina on Copper With Acid

Clean the Copper

• 1

  Pour the warm water in a bucket.

• 2

  Add ammonia and dish detergent. Mix well.

• 3

  Soak a lint-free cloth in the mixture. Ring out to remove access liquid and scrub the copper surface to remove any debris, dirt, grease or oil residues. This process may need to be repeated several times. Rinse the cloth under clean, warm water before resoaking it.

• 4

  Thoroughly dry the copper using a clean, lint-free cloth.

• 5

  Test the copper for any remaining residue. Pour clean water over the surface. If the water beads in any location, that spot will need to be cleaned again.

• 6

  Remove any oxide film that has already occurred on the surface of the copper, as this will cause the patina acid to adhere poorly. Use a cold-water solution of 5 to 10 percent sulfuric acid to wipe the surface clean.

Applying Patina Acid to Copper

• 7

  Use a strong, acid-resisting plastic bucket to prepare the patina acid. Dissolve the ammonia sulfate in water, then add the copper sulfate.

• 8

  Slowly add the concentrated ammonia while stirring constantly.

• 9

  Using a commercial-grade automotive funnel, fill a galvanized steel garden tank sprayer with the acid solution.

• 10

  Spray the area rapidly using a fine mist setting. Avoid making large drops as these run together.

• 11

  Allow the copper to dry for at least 10 minutes before reapplying. Reapply at least five times. Patina will not appear immediately. Once spraying has been completed, the surface of the copper will appear "glassy" and resemble a dark coat of varnish. If the copper becomes wet within six to eight hours of applying the patina acid, it could be washed away and the process will need to be repeated.