How to Age Copper

As it ages, copper reacts to the natural elements in the surrounding atmosphere to take on a greenish patina. However, when allowed to age naturally, the verdigris patina will take years to develop, especially in dry climates. If you know how to age copper artificially, however, you can achieve the same effect almost overnight. The process is simple, and you can use common household supplies, rather than harsh or dangerous chemicals.

1. Spray a commercial ammonia-based window cleaner on the copper item you want to patina. Wipe the surface completely with a lint-free cloth. Be sure to clean the entire surface, including small crevices. For the aging process to be effective, the copper must be free of oils and other surface contaminants.
   
   
2. Mix one of two aging compounds. Pour the mixture into a spray bottle. You will achieve the best verdigris results with salt that has no added iodine.
   
   
   • One option is to blend 1/4 cup (.19 liter) each of lemon juice, household ammonia, white vinegar and salt. Stir or shake thoroughly.
   • An alternative is to put 1 cup (.24 liter) white vinegar, 3/4 cup (.18 liter) household ammonia and 1/4 cup (.19 liter) table salt in the spray bottle. Shake it to mix the ingredients thoroughly.
3. Spray the copper lightly with the window cleaner again, but do not wipe it off this time. This serves to break the invisible surface tension so that the aging compound makes solid contact with the metal itself.
   
   
4. Cover the entire surface with the patina mixture, making sure to get into even the smallest spaces. Do not over-saturate the piece, but be certain that you have covered all of the metal.
   
   
5. Place the copper item in a plastic bag or tent it with plastic to create an artificial high humidity level, if the humidity is low. Allow it to sit, undisturbed, for about 1 hour. If you live in an area with high humidity or if you apply the mixture during a rainstorm, you do not need the plastic's artificial environment.
   
   
6. Remove the item from the plastic and apply the patina mix again, once more making certain that you have covered the entire metallic surface. Return it to the humidifying bag or tent, and allow it to rest overnight.
   
   
7. Apply the mixture again and allow it to work on the metal overnight, if necessary for the degree of aging you desire.
   
   

• Once you know how to age copper, you can experiment with using the patina like another tool. Before you spray the oxidizing mixture on the copper, mask off some areas with paper or tape to create design elements on the surface.
• For larger or smaller projects, maintain the same ratios for the ingredients to produce more or less of the aging solution.

• Use ammonia products only outdoors or in well-ventilated areas, as the fumes can be toxic.

• Window cleaner
• Lint-free cloth
• Lemon juice (optional)
• Household ammonia
• Vinegar
• Salt
• Plastic bag