How to Remove Copper on the Surface of Materials

Co-authored by wikiHow Staff

Last Updated: December 6, 2022

Copper is a valuable metal with many uses. Because of its high demand and versatility, many things that used to be made of solid copper are now being made of other materials and simply plated (or covered) with copper on the outside. This copper plating can be removed by dissolving the copper with specific chemicals, or by grinding it off. Just be careful not to damage the material underneath.

Method 1

Method 1 of 3:

Dissolving Copper with Household Products

1
Pour hydrogen peroxide in a glass. Hydrogen peroxide will help to oxidize the copper. Unfortunately, it can degrade pretty quickly, making your solution weaker. Start off with about 30 mL of hydrogen peroxide in a beaker.^{[1]
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- You can add more hydrogen peroxide to keep the reaction going longer. This will be necessary if you have a lot of material (more than the size of a penny).
- You should use a solution of 35% hydrogen peroxide or stronger.
2
Add vinegar. Add twice as much vinegar as you did hydrogen peroxide. The vinegar will help to make the solution more acidic. This will act on the copper ions that are formed by the hydrogen peroxide oxidation.^{[2]
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- For example, if you add 30 mL of hydrogen peroxide, you will need 60 mL of vinegar.
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3
Submerge the material. When you submerge the material, you will start to see bubbling. This is an indication that the reaction is going. As the reaction proceeds, you will start to notice the solution turn blue.^{[3]
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- Note that this reaction takes a long time, and it is not particularly effective. If you have a large object or a thick layer of copper, another method should be used. Just to remove the copper from a penny it could take hours or days.
- Remove the object when you are finished and pour the solution into a labeled bottle. The solution should be turned over to a professional waste contractor.

Method 2

Method 2 of 3:

Ionizing Copper with Concentrated Acid

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Put the material in a glass beaker. Add your copper coated material to a glass beaker. If it is too large to fit in a beaker, use a glass tub or tray. Place the glass container outside or underneath a fume hood before proceeding.^{[4]
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- Plastics and many metals will be dissolved using this method. Only place items that are made from gold, platinum, iron, nickel, aluminum, chromium, or cobalt in the beaker.
2
Add the nitric acid to the beaker. Pour concentrated nitric acid in the beaker. You should pour enough to cover the surface of the material that you are cleaning. You will see a dark gas form above the surface of the liquid. This is nitrogen dioxide gas.^{[5]
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- Nitric acid is a strong acid. Wear gloves and goggles. Do not get the acid on your skin or in your eyes. Do not inhale fumes from the acid, and do not ingest it.
- Nitrogen dioxide is toxic. This must be done in a fume hood or other well ventilated area. Do not inhale the nitrogen dioxide.
- If you do get the acid on your skin or eyes, wash with water for 15 minutes.
3
Pour in water. When the reaction has completed, pour water into the beaker or flask. This will dilute the copper ions and create a light blue color. It will also dilute any excess acid and allow you to retrieve the remaining material.^{[6]
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- You should use tongs to remove the material. Do not put your hand in the solution!
- The reaction is complete when no more gas is being formed.

Method 3

Method 3 of 3:

Grinding Down Copper

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Select a grinding tool. Depending on the size of the object you plan to grind, you might use a grinding wheel, a sander, or even a sand blaster. A sander is best suited for minimal abrasion to break through a thin layer of copper. A grinding wheel will be more aggressive and help you cut through a thicker layer of copper, but the sandblaster will be ideal for removing copper from a larger object.
- You should also consider the material underneath the copper. If you are dealing with a soft metal or plastic, a grinding wheel might do more damage than a sander or sand blaster.
2
Grind the copper from the surface. Grinding removes the copper layer mechanically instead of chemically. This means that you will likely have to press pretty hard with a sander or grinding wheel. You should also be wearing goggles and a respirator.^{[7]
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- Inhaling metal shavings can be dangerous.
- Metal shavings can cut your eyes if they get in them.
3
Smooth the material underneath. Once you have removed the copper layer, you will notice grooves and marks left on the material underneath. This happens because once you break through the copper layer, you begin to grind the surface of the material. Smooth out the surface of the material by sanding those grooves down with a finer sandpaper, and wiping the surface clean.^{[8]
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- For example, you might use a 180 grit sandpaper to get out the initial scratches, and the move to a 300 grit sandpaper to smooth things out even more (a higher grit produces finer scratches).
4
Polish any metal underneath. If you are removing copper from the surface of another metal, you might need to polish that metal afterward. Most metals have specific polishes that you can buy commercially, such as aluminum polish or chrome polish. Apply the polish according to the manufacturer's instructions to make your metal shine and protect it from the environment.

Warnings

Nitric acid is very corrosive.

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Do not consume any of the reactants.

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Wear gloves and goggles for all methods.

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Nitrogen dioxide gas is poisonous.

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