How to Oxidize Copper

Boil 2 or more eggs thoroughly. Usually, two or three boiled eggs are sufficient unless you're oxidizing a large amount of copper. Place the eggs, still in their shells, into a pot of water and let it boil for at least 10 minutes. Don't worry about overcooking the eggs. In fact, well-boiled eggs with a green ring inside and the sulfur smell are exactly what you need, as sulfur helps to alter the appearance of copper.

Use tongs to place the eggs in a plastic bag. Place the eggs in the plastic bag, and if possible, use one with a zip closure for better sealing. Use tongs or any other tool to handle the eggs as they will be very hot. If you don't have a plastic bag that fits your copper item, you can use a food container, bucket, or any other container that can be sealed. More eggs may be needed if using a larger container.

• It's best to use a clear container so you can monitor the appearance of your copper without opening it.

Crush the eggs. Close the bag loosely before crushing the eggs to prevent them from spilling. Use a spoon, the bottom of a cup, or any heavy object to crush the eggs. Break the entire shell, egg white, and yolk into small pieces.

• Don’t seal the bag completely; otherwise, the air inside will make it more difficult to crush the eggs.

Place the copper item on a small plate. The plate will keep the copper item separate from the eggs. This way, you won’t have to clean the copper after and avoid any marks caused by the eggs touching the metal.

Put the copper item in the bag and seal it. Place the plate with the copper item into the plastic bag, positioning it close to or far from the crushed eggs as long as they don’t touch. Close the bag tightly or tie it if you're using another container to trap the sulfur gas inside. The bag will inflate due to the heat from the eggs, but it usually won’t break from the pressure.

Check periodically to see if the item has reached the desired color. You might notice results after placing the item in the bag for just 15 minutes, but typically, it takes 4-8 hours for the copper to turn dark brown. The longer the item remains in the bag, the darker it will become, and the larger surfaces will develop a naturally uneven antique look. Remove the item once it achieves the desired appearance.

• Wash the item to remove any egg fragments and admire its appearance once cleaned.

Scrub the copper item with a scouring pad and water. Use long, sweeping motions to create a smooth, even patina on the surface, ensuring the copper oxidizes uniformly without blotches. You may skip this step or try it on clean areas of the copper if you're aiming to create a piece with a contrast between new and aged elements.

Clean the copper item with a gentle dish soap solution and rinse off the soap. Remove any soap, oil, and residue from the surface. Dry the item with a soft cloth.

Mix the solution to achieve the desired color. There are various solutions you can use to oxidize copper, depending on the color you want to achieve. Some of the solutions listed here involve common household ingredients or items available at many stores.

• Warning: Always wear rubber gloves and work in a well-ventilated area when using ammonia. Protective goggles and a respirator mask are recommended. Be prepared to rinse your skin or eyes under running water for 15 minutes if chemical exposure occurs.
• To achieve a greenish patina, mix 2 cups (480 ml) of white vinegar, 1.5 cups (360 ml) of ammonia (unscented and without soap), and 0.5 cup (120 ml) of non-iodized salt. Mix the ingredients in a spray bottle until the salt dissolves. Use less salt if you want a lighter green patina.
• For a brown patina, dissolve baking soda in hot water in a spray bottle until no more baking soda can dissolve.
• You can also purchase a ready-made copper aging solution and follow the instructions on the packaging to achieve your desired color. Liver of Sulphur is a popular product used to age copper.

Take the copper item outside or to a well-ventilated area before working with chemicals. Lay down newspaper underneath to protect the surface you're working on.

Spray the solution onto the surface of the item at least twice a day. Apply the solution to the copper item and wait an hour to see if there are any changes. If you see some progress, continue spraying once every hour, focusing on the areas where the oxidation hasn't settled. Alternatively, you can spray twice a day until the patina becomes visible. Place the item outside during this time to speed up the oxidation process.

• If you wish to target specific areas for patina formation, use a Scotch-Brite pad, a brass-bristled brush, or cotton swabs to scrub the surface after spraying the solution. Wear gloves and protective glasses if the solution contains ammonia, acids, or other hazardous chemicals.
• If you're in a dry climate, cover the item with a plastic bag or plastic sheet to maintain moisture. Place a plastic cover over the frame to prevent direct contact with the copper.

Create a green and blue patina using Miracle Gro fertilizer. You can use concentrated Miracle Gro fertilizer to oxidize copper quickly. Mix 1 part Miracle Gro with 3 parts water for a blueish patina, or with red wine vinegar for a greener hue. Use a spray bottle or cloth to apply the solution to the copper's surface randomly for a naturally aged look. The patina will start forming in about 30 minutes and will reach a more stable state within 24 hours.

Soak copper in white vinegar. White vinegar can create a greenish or bluish patina, but it requires another material to keep moisture in contact with the copper surface. Soak the copper item in a mixture of white vinegar and salt, or bury it in sawdust, or even crushed potato chips, then soak it in the vinegar. Place everything in a sealed container for 2-8 hours, then remove and air dry. Use a soft brush to clean off any debris.

Create a bright blue patina using ammonia fumes and salt. Pour unscented ammonia (without soap) into a bucket until it reaches 1.5 cm. Do this outdoors or in a well-ventilated area. Spray saltwater onto the copper item and place it on a wooden block above the ammonia level. Cover the bucket and check after 1-2 hours, or until the copper turns dark brown or blue. Remove the item from the bucket and air dry it until a bright blue patina forms on the surface.

• Warning: Always wear protective goggles and gloves when working with ammonia. Do not reuse the container that held ammonia for water or food storage.
• The more salt you use, the more vibrant the color will appear.

• The newly formed copper patina will last longer if you apply a copper polish or wax to its surface. Avoid using water-based products on the ammonia-induced patina.
• Always mix solutions in containers designated specifically for copper treatment; this includes spray bottles as well.
• If you have a chemical kit, consider experimenting with the copper patina solutions from this list. Please note, these formulas are collected from multiple sources and may yield unexpected colors.

• Never mix ammonia with bleach or other household cleaning products.
• When working with ammonia, especially indoors, ensure you're in a well-ventilated space. Be cautious to avoid ammonia splashing into your eyes.

• Scrubbing pad
• Gentle dish soap
• Spray bottle
• Container with a tight-fitting lid
• Copper polish or wax (to protect the patina)

One or more of the following ingredients:

• Water
• Salt
• Vinegar
• Miracle Gro fertilizer
• Baking soda
• Ammonia