Oxidizing Copper

Oxidize Copper Step 1 Version 7.jpgTwo or three eggs should be plenty unless you have a large amount of copper to oxidize. Place them with their shells intact in a pot of water and bring to a boil for at least ten minutes. Don't worry about over-boiling them. In fact, that over-done greenish ring and sulfur smell is exactly what you need, since the sulfur will alter the appearance of your copper.

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Use tongs to place the eggs in a plastic bag. Transfer the eggs into a plastic bag, preferably one that can be sealed, such as a ziploc. Use tongs or another utensil to pick up the eggs, since they will be hot. If you don't have a bag that can fit your copper object comfortably, use Tupperware, a bucket, or any other container that can be sealed shut or have a lid placed over it.Oxidize Copper Step 2 Version 7.jpg Large containers will require a large amount of eggs.
  • Ideally, your container should be transparent so you can check on the appearance of your copper without having to open the container.
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. This will prevent them from coming into contact with the eggs.Oxidize Copper Step 5 Version 7.jpg Besides letting you avoid washing the egg off afterward, this will also prevent spots where the egg touches the metal.

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, as long as they are not 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. The bag will expand due to the heat of the eggs, but this shouldn't be enough to break most plastic bags.

Check regularly to see if the desired appearance has been reached. You may start to see results as soon as 15 minutes after you put the copper in the bag, but the copper often takes 4–8 hours to reach a dark brown appearance. The copper should grow darker the longer it remains in the bag, and large surfaces will acquire an aged, uneven appearance. Remove when 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.
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