Copper is a common metal found in everything from pipes and wires to cookware and jewelry. While it has many useful properties, there are times when you may need to remove or dissolve copper coatings or objects. Instead of using expensive chemicals or abrasive methods, there are several inexpensive ways to dissolve copper using common household ingredients.
Dissolving Copper
Before diving into the specifics, let’s go over some copper dissolving basics.
- Why Would You Need to Dissolve Copper? Some reasons you may want to remove copper include: salvaging copper from scrap, removing copper plating, cleaning copper surfaces, extracting copper from ore, and more.
- How Does Copper Dissolve? Copper dissolves when it undergoes a chemical reaction with an acid or oxidizer. This produces copper ions which dissolve into the solution.
- What Type of Chemicals Can Dissolve Copper? Strong acids like sulfuric acid, nitric acid, and hydrochloric acid can dissolve copper. Weaker acids like acetic acid (vinegar) can also react with copper when hydrogen peroxide is added as an oxidizer.
- Is Dissolving Copper Dangerous? Yes, proper safety precautions need to be taken when working with chemicals and dissolved metal ions. Wear protective equipment like goggles, gloves, and a mask. Work in a well-ventilated area.
Now let’s look at some of the most affordable ways to dissolve copper without breaking the bank.
Dissolving Copper with Vinegar and Hydrogen Peroxide
One of the simplest ways to dissolve copper is by using plain old white vinegar and hydrogen peroxide. Here is how to do it:
What You Need
- White vinegar
- 3% hydrogen peroxide solution
- Glass or plastic container
- Copper-coated object
Step-by-Step Method
- Pour approximately 1 cup (250mL) of white vinegar into the container.
- Add 1/2 cup (125mL) of 3% hydrogen peroxide solution.
- Place the copper item in the vinegar-peroxide mixture, making sure it is fully submerged.
- Allow the copper object to soak for at least 8 hours, up to 24 hours.
- Check on the item periodically. You should see bubbles forming on the surface as the peroxide reacts with the acetic acid in the vinegar.
- Once the copper coating has dissolved, remove the item from the solution. Rinse it off with water.
How This Method Works
Vinegar contains acetic acid, which reacts with copper to form copper acetate. This reaction alone happens very slowly. Adding hydrogen peroxide accelerates the reaction. The peroxide acts as an oxidizing agent, stripping electrons from the copper atoms and allowing them to be dissolved by the acetic acid.
While not as fast as harsh mineral acids, this method provides a cheaper, safer way to dissolve copper with ingredients you probably already have at home. It works best for items with thin copper coatings rather than solid copper. Adjust the vinegar/peroxide ratios and soak times as needed.
Using Lemon Juice and Salt to Dissolve Copper
Lemons contain citric acid that can dissolve copper like acetic acid. The addition of salt accelerates the reaction. Here is how to dissolve copper with lemon juice and salt:
What You Need
- Fresh lemon juice
- Table salt
- Glass or plastic container
- Copper item
Step-by-Step Method
- Squeeze enough lemons to produce approximately 1 cup (250mL) of juice.
- Pour the lemon juice into the container.
- Add 2 tablespoons (30mL) of table salt and stir to dissolve.
- Place the copper item in the lemon juice-salt mixture.
- Allow the item to soak for at least 12 hours.
- Check periodically and remove the item once the copper coating has dissolved.
- Rinse with water to remove any remaining solution.
How This Method Works
Like vinegar, lemon juice contains an acid – citric acid – that reacts with copper to form copper citrate. The salt helps to ionize the copper, making the metal atoms release more easily from the surface. This speeds up the reaction so less soak time is required compared to using lemon juice alone.
Lemon juice and salt provide a non-toxic way to dissolve thin layers of copper. It works well for items like jewelry or coins when you don’t want to damage the surface underneath the copper plating. Adjust the lemon juice/salt ratios as needed.
Cleaning Copper Pipes and Wires with Muriatic Acid
For dissolving thicker copper coatings, a stronger acid is needed. Muriatic acid (hydrochloric acid) is commonly used to clean bricks and concrete, but it also reacts with copper. Here is how to use it to dissolve copper pipes or wiring:
What You Need
- Muriatic acid (31-35% hydrochloric acid)
- Acid-resistant container
- Copper pipe section or wires
- Protective gear – gloves, goggles, mask
Step-by-Step Method
- Put on all protective gear before handling muriatic acid!
- Work in a well-ventilated area outdoors.
- Place the copper item in the acid-resistant container.
- Carefully pour enough muriatic acid over the copper item to submerge it.
- Allow the copper to soak for at least 3 hours. More time may be needed for thicker coatings.
- Remove the item from the acid solution and rinse thoroughly with water.
- Neutralize any remaining acid by pouring baking soda and water over the surface.
- Dispose of the used acid properly. Do not pour it down a drain!
How This Method Works
Muriatic acid contains hydrochloric acid, a strong inorganic acid that readily reacts with copper metal. This produces copper chloride which dissolves into the solution as copper ions. The acid essentially corrodes away the copper surface.
While very effective at dissolving copper, muriatic acid is also dangerous and must be handled with extreme care. Never use this method without proper safety gear and in a well-ventilated outdoor area. It works well for removing copper from pipes and wires when needed.
Mechanical Removal of Copper
Instead of chemicals, copper can also be removed mechanically using tools to grind, sand, or abrade away the surface. Here are some options:
Sanding
- Use a belt sander or orbital sander with 60-100 grit sandpaper to remove copper plating.
- Work in one direction only to avoid scratches.
- Finish by sanding with 220-400 grit paper to smooth and polish the surface underneath.
Grinding
- Use an angle grinder or rotary tool with a metal grinding wheel to grind off copper coating.
- Keep the tool moving constantly to avoid damaging the metal underneath.
- Finish with a finer grit wheel or sandpaper.
Sandblasting
- Rent or buy a small sandblaster to direct high-powered air and abrasive media at the copper surface.
- Glass beads, baking soda, or fine grit works well to remove copper.
- Contain the blast area and wear a respirator to avoid inhaling particles.
Filing
- For small items, use a metal file to manually scrape away the copper layer.
- Work in straight strokes going against the grain of the metal.
- Finish by smoothing with fine grit sandpaper.
While mechanical removal requires more physical effort, it avoids the risks and disposal issues of chemicals. It also gives you more control over the final polished surface. Use the least abrasive method needed to remove the copper efficiently.
Dissolving Copper Safely
Whichever method you choose, take appropriate safety precautions when dissolving copper:
- Wear protective eye goggles, gloves, and clothing.
- Work in a well-ventilated area. Avoid breathing fumes.
- Handle acids very carefully by following directions.
- Dispose of waste properly. Neutralize and dilute acids before disposal.
- Store chemicals securely in sealed containers.
- Never mix or dispose of chemicals down a household drain.
- Rinse dissolved copper thoroughly from surfaces and skin.
- Research your local hazardous waste disposal regulations.
Taking the right safety measures allows you to dissolve copper using common chemicals and tools affordably without harming yourself or the environment.
Choosing the Best Method for Your Project
Here is a quick recap of inexpensive copper dissolving options:
- Vinegar and Peroxide: Best for gently removing thin copper coatings from household items.
- Lemon Juice and Salt: A non-toxic option for dissolving copper without damage.
- Muriatic Acid: Quickly dissolves thicker copper but requires safe handling.
- Mechanical Removal: Avoids chemicals entirely but requires more physical effort.
Choose based on your specific copper removal needs:
- Type and thickness of the copper coating
- Size and number of items needing copper removal
- Desired condition of the metal underneath
- Your safety experience with chemicals
- Access to proper protective equipment
- Appropriate ventilation
- How you will dispose of waste
With the right approach, you can efficiently and affordably dissolve copper in your projects using common household ingredients or tools. Just be sure to take all necessary precautions!
References
- Lu, Qin, et al. “A Review of Chemical Dissolution Methods for Copper Recovery.” Hydrometallurgy, vol. 199, 2020, p. 105297., https://doi.org/10.1016/j.hydromet.2019.105297.
- Agrawal, A., et al. “An Overview of Chemical Methods for the Synthesis of Copper Nanoparticles.” RSC Advances, vol. 5, no. 115, 2015, pp. 94410–94420., https://doi.org/10.1039/c5ra20760c.
- “Copper Mining and Extraction: Oxide Ores.” Copper Mining and Extraction: Oxide Ores, www.copper.org/education/resources/copper-mining-extraction/.
- Dean, John A. Lange’s Handbook of Chemistry. 15th ed., McGraw-Hill, 1999.
- Kumar, S. “Study on Mechanical and Chemical Methods for Surface Defect Detection of Rolled Products.” Journal of Nondestructive Evaluation, vol. 37, no. 2, 2018, https://doi.org/10.1007/s10921-018-0472-6.
- Muresan, L., et al. “Chemical Versus Electrochemical Methods for Cleaning Copper and Bronze Coins.” International Journal of Conservation Science, vol. 7, 2016, pp. 147–154., www.ijcs.uaic.ro/public/IJCS-16-09_Muresan.pdf.
- “Copper: Chemical Properties and Common Uses.” Study.com, Study.com, study.com/academy/lesson/copper-chemical-properties-and-common-uses.html.
- Martell, Arthur E., and Robert M. Smith. Critical Stability Constants: Inorganic Complexes. Springer US, 1974.
- Cotton, F. Albert, and Geoffrey Wilkinson. Advanced Inorganic Chemistry: A Comprehensive Text. Wiley, 1980.
