Shiny copper looks good on the bottom of pots and pans hanging from a pot rack in the kitchen, but for arts and crafts projects, an aged copper look – like the green patina that covers the Statue of Liberty – may be more to your liking. Time and humidity gives copper the aged look, but you can also achieve it artificially when you don't want to wait. Wear old clothing, rubber gloves and goggles to protect yourself while you work. Even novice crafters can age copper artificially and safely with ingredients found in the home.
For this project you'll need a quart spray bottle, a smaller spray bottle, rubbing alcohol, warm water, ammonia, a grease-fighting detergent, a soft cloth,lemon juice, iodine-free salt and a large plastic trash bag with tie. Some of the ingredients combine to clean the copper, while others create the agent used to age the copper.
Ammonia Cleaning Agent
Remove lacquer coatings with acetone, nail polish remover or a commercial paint thinner. Wear rubber gloves while you work to avoid your skin oils from transferring to the copper. Mix 1/2 cup of 70-percent rubbing alcohol – isopropyl alcohol – in a quart spray bottle with 26 ounces of warm water, 2 tablespoons of ammonia and 1/4 teaspoon of a grease-fighting detergent. Spray the mixture on the copper to clean it. Wipe off with a soft lint-free cloth.
Homemade Aging Mixture
Just as it takes time to give copper a green patina, you must repeat the aging process with a homemade compound. After making the copper compound, you will need to apply it to the copper, allow it time to work and repeat the process as necessary until you achieve the desired results. The large plastic trash bag and tie allows you to create an artificial humid environment to speed up the process.
In a plastic spray bottle, combine equal amounts of white distilled vinegar, lemon juice, household ammonia and salt without iodine in the bottle. Avoid salt that contains iodine for the best results, as iodized salt results in less of a green patina. If you don't have lemon juice, use more ammonia and vinegar to replace it, but lemon juice also helps to age the copper quicker.
The Aging Process
First, spray the copper item – while wearing rubber gloves – with the alcohol glass-cleaning agent you first used to clean it. Let this sit on the surface of the copper item. Spray the item with the aging mixture and let it sit on the copper. If you live in a humid climate already, you can skip the next step. After spraying the copper item with the aging mixture, set it inside a plastic bag and tie it off. This creates a simulated humid environment, which helps to speed the process. Let it sit for several hours. Repeat the aging process as needed. While it may result in a green patina on the first attempt, some of the patina may come off with cleaning. Repeated coatings and waiting periods produce a better result.
Dark Brown Copper
To achieve a dark brown color, hard-boil two eggs. Break up the hard-boiled eggs into bits – shells and all – with a fork and place them inside a small open container inserted into a larger one with a lid. Place your copper item inside the seal container, ensuring that the hard-boiled eggs do not touch the copper. The sulfides in the hard-boiled eggs react with the copper to give it a brown appearance, but it may take several days to work. Add more eggs as necessary.