How to Oxidize Copper at Home

• Boil some eggs and crush them inside of a plastic bag. Set the copper item inside and wait 4-24 hours for the patina to develop.
• For a more hands-on option, soak the item with white vinegar, ammonia, and salt for a green patina. Use baking soda for a brown patina.
• Looking for a unique color? Soak the item in liver of sulfur for a deeper, more dynamic blue hue.

The Hard-Boiled Egg Method

Hard boil 2-3 eggs. This process works best with jewelry and smaller objects. Place your eggs (with their shells intact) in a pot of water and boil the eggs for at least 10 minutes. Don't worry about over-boiling them. In fact, that over-done greenish ring and sulfur smell is exactly what you need—the sulfur from the eggs will alter the appearance of your copper. This process will produce a brown patina, comparable to the color and texture you’d see on a penny.

Use tongs to set the eggs in a plastic bag. Cool the eggs under a stream of cold water for a few seconds. Grab a sealable plastic bag and use tongs to transfer the eggs to the inside of the bag. If you don't have a bag that can fit your copper object comfortably, any sealable plastic container will work. Ideally, use a container or bag that’s transparent so you can check on the appearance of your copper as you wait.

Mash your eggs into pieces. Seal the bag halfway closed before you begin to avoid spraying egg through the opening. Hit the eggs through the plastic bag with a spoon, the base of a cup, or any heavy object. Crush the shell, white, and yolk until it is mashed into many pieces. Don't seal the bag all the way, or the air pocket will make it difficult to break the egg.

Place your copper objects on a small dish (optional). If you don’t want your copper to get egg on it, get a small dish that will fit inside of the bag. This will keep the egg from touching your item in the bag. You’re going to clean the copper off anyway, so feel free to skip this step if you’d like.

Put the dish inside the bag and seal it closed. Place the dish containing your copper object inside the plastic bag. It does not matter whether it is near the mashed-up egg pieces or not so long as the eggs aren’t touching the copper. Seal or tie the bag closed to trap the sulfur fumes inside, or attach the lid if you are using a container. If you want the patina to finish more evenly, clean the copper item by scrubbing it with soap and water before putting it in the bag. The bag will expand due to the heat of the eggs. This is normal and it’s nothing to worry about.

Wait 4-24 hours for the patina to develop. You may start to see results in 15 minutes or so, but copper will normally take at least 4 hours to begin developing a dark brown appearance. The copper will grow darker the longer you leave it in the bag. Remove the item once you've achieved the look you were going for. Wash the copper item afterward to remove any pieces of egg and to see what the item looks like when clean. Don’t eat the eggs. We’re sure they smell delicious at this point, but they’re not safe to eat or use.

Traditional Cleaning Solutions

Scrub the copper item with an abrasive pad and water. Run the copper item under warm water. Grab some steel wool or a cleaning pad and scrub the copper in the direction of the grain. You can use soap or baking soda if the item is uniquely dirty. Continue scrubbing until the surface is smooth and clean. You can skip this part if you intentionally want an uneven finish or you’re experimenting with copper oxidization for art.

Prepare a solution based on the color you want to achieve. There are several efficient solutions you can use to oxidize copper. Choose a solution based on the final color you are trying to achieve. Just make sure you wear rubber gloves and work in a well-ventilated area—especially if you’re working with ammonia. Green Patina: Mix 2 cups (480 mL) white vinegar, 1.5 cups (360 mL) pure ammonia, and 0.5 cups (120 mL) non-iodized salt. Mix in a plastic spray bottle until the salt dissolves. Use less salt to reduce the amount of green in the patina. Brown Patina: Mix 1-part baking soda with 1-part hot water in a spray bottle. Deep Blue/Brown Patina: Purchase a bottle of liver of sulfur.

Set the copper item up in a well-ventilated area. You can work outdoors or in an indoor area with all of the windows open—whatever seems easier for you. Spread newspapers out underneath the item to protect the surface it’s on from overspray or spills.

Keep applying the solution till you have a patina you like. Spray the copper with the solution and wait a few hours to see how it develops. If you like the color you’ve got, let the item air dry for 24 hours and you’re done! Otherwise, continue to spray hourly, focusing on portions where the patina didn't hold. Continue spraying until you’re happy with the patina. If you want to have more control over exactly where and how the patina forms, scrub the item with steel wool or a cotton swab after spraying. Wear gloves and safety glasses if you do this. If you are in a low-humidity area, place a plastic bag or sheet over the item to trap the moisture. Use a frame or drape it between larger objects so the plastic does not come in contact with the copper. Let the item air dry for 24 hours when you’re done and rinse it under warm water to clean it.

Experimental Options

Make your copper green and blue with Miracle-Gro. You can use concentrated Miracle Gro plant fertilizer to oxidize your copper quickly. Mix approximately one part Miracle Gro with 3-parts water for a bluer patina, or with 3-parts red wine vinegar for a greener one. Apply with a spray bottle or rag, doing so unevenly if you want to create a more natural, aged appearance. You can soak the item for up to 24 hours if you want a deeper hue.

Coat copper in white vinegar for a varied blue-green look. Let the copper soak in a mixture of white vinegar and salt. Alternatively, you can bury the item in sawdust or crushed potato chips, then soak the mixture with vinegar. Place in a sealed container for 2–8 hours. Check on the color regularly. Once you’re happy with the hue, take the item out and air dry it. Use a soft brush to gently remove solid materials.

Create a bright blue color using ammonia vapors and salt. Go outdoors or in a well-ventilated area. Fill the bottom of a bowl or sheet pan with about ⁄2 in (1.3 cm) of ammonia. Spray the copper with salt wate, and place it over the ammonia on a wire rack or block of wood. Cover the container and check back every hour or two until the copper is dark brown with hints of blue. Remove the item when you’re happy with the color and rinse it off under water. Always wear gloves and safety glasses when handling ammonia. Do not use the container that held ammonia to hold food or water without washing it first. The more salt you use, the more noticeable the color will be.