How to Antique Copper to Brown

Giver copper objects the feeling of antiques with brown patinas.

The reverence sculptors, jewelers and other metal smiths have for copper comes largely from its malleability and its rich, lustrous, gold tone. When copper ages or has exposure to various chemicals, it develops a patina. Depending on the circumstances, patinas come in many colors, including green, blue, purple, red and black. To imbue copper with a darker, earthen quality, give it a brown patina. Leave copper with a rich, antique brown patina using a ferric nitrate solution.

Things You'll Need

• Long-sleeve shirt
• Rubber gloves
• Safety glasses
• Face mask
• Ferric nitrite
• Glass beaker or plastic tub
• Nonreactive metal rod
• Plastic spray bottle (optional)
• Patina stand (optional)
• Table vice (optional)
• Crucible tongs (optional)
• Torch
• Welding mask (optional)
• Leather work boots (optional)
• Flint torch igniter
• Paintbrush (optional)

Instructions

1. Wear a long-sleeve shirt and put on protective, rubber gloves. Put on protective glasses and a chemical-filtering face mask.

2. Add 1/2 teaspoon. of ferric nitrate per pint of distilled water. To create a brush-on solution, combine the ingredients in a glass jar, beaker or a plastic tub. Stir the solution with a metal rod until the ferric nitrate dissolves. To create a spray-on solution, pour the mixture into a spray bottle.

3. Remove the rubber gloves and place the copper object on a heat-resistant work surface. If necessary, elevate or stand up the item with a patina stand. Objects can also be gripped in a table vice. Hold smaller objects with crucible tongs. Wear heat-resistant, leather, work gloves when heating while holding tongs to prevent heat transference through the tongs from causing hand burns.

4. Turn on the fuel for a torch to heat the copper. Heat copper with a propane, butane or oxyacetylene torch. Wear a welding mask and leather work boots when working with an oxyacetylene torch. Squeeze a flint torch igniter in front of the gas to spark the flame.

5. Hold the flame to the copper for several seconds to heat the copper. Work in small sections at a time for larger objects. Once heated, spray or brush the heated area with the patina solution. The copper should be hot enough to cause the solution to steam. If the solution does not steam, heat the copper for a few more seconds.

6. Continue switching back and forth between heating and applying the patina solution to cover the entire object. Ferric nitrate patinas are transparent. Build up several patina layers until the desired depth of brown is reached.

References

• Science Company: Patina Formulas for Brass, Bronze and Copper
• David M Bowman Studio: Formulas

Resources

• RobotWorx: How to Operate an Oxyacetylene Torch