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How to Restore a Coin to Mint Condition

Restoring coins to top condition can increase the coins̵7; value and improve a coin collector̵7;s collection for display. There are a number of ways to clean coins, each of which depends on the kind of coin, what kind of equipment and expertise is available, what sort of corrosion the coin suffered and for how long. Cupreous metals are those that are comprised either entirely of copper or metal alloys of which copper is a major component. Dimes and quarters (92 percent copper, 8 percent nickel) as well as nickels (75 percent copper, 25 percent nickel) are all cupreous metals. They can withstand long immersion in saltwater, and can be cleaned in a number of ways, including electrolytic reduction and chemical treatment. The penny, as it is currently minted, is comprised of 97.5 percent zinc and 2.5 percent copper. Copper oxide rust develops over time as the penny is exposed to air and water. It can be removed with a weak acidic solution.

Things You'll Need

Sodium hydroxide (NaOH)
Small plastic container
Tap water
Electrodes
Benzotriazole
White vinegar
Table salt

Instructions

Electrolytic Reduction
- 1
  Create an electrolyte consisting of 2 percent concentrated sodium hydroxide (NaOH) and tap water.
- 2
  Place the electrolyte into a contained area, such as a small, plastic container.
- 3
  Place two electrodes into the electrolytic container.
- 4
  Place a coin into the electrolytic container.
- 5
  Connect the two electrodes so the anode, or positive end, is the electrolytic container, and the cathode, or negative end, is the coin.
- 6
  When the electric current goes through the container and the coin, the positive charged ions in the coin ̵1; including some of what comprises the rust and dirt on the coin ̵1; are repelled from the coin.
- 7
  Repeat steps 1 through 6 with different PH levels and currents. Expertise and familiarity with electric currents is recommend for safety and optimal cleaning.
Chemical Treatment (Benzotriazole)
- 8
  Put on gloves to avoid direct contact with benzotriazole (BTA).
- 9
  Dissolve 1 to 3 percent concentrated BTA in ethanol or water.
- 10
  Drop the dimes, nickels and quarters in the solution.
- 11
  Although not necessary, for best results leave the objects in the solution under a vacuum for 24 hours or more.
- 12
  Remove the objects from the solution and wipe off the coins with a rag dipped in ethanol.
Restoring Pennies
- 13
  Mix 1 teaspoon of table salt with 1/4 cup of white vinegar in a glass or any non-metallic bowl. Mix the salt in until it is dissolved into the vinegar.
- 14
  Drop the pennies you want to clean into the solution.
- 15
  Let the pennies sit in the solution for between five and 10 minutes.
- 16
  Remove the pennies and rinse them thoroughly in water immediately.
- 17
  Air dry the pennies on a paper towel.

Coin Collecting