8/17/2023 0 Comments Old copper coinsThe Same Coin After Cleaning and Patination Here is the case of dug copper coin that was immersed into Ammonia solution for a few hours and then patinated. A brief immersion in a 5% hydrochloric acid for neutralization should follow immediately. Great care must be exercised here as the coins might be damaged if they are exposed to the air for a long moment while being transferred from the ammonia bath to the acid bath. They can be darkened if desired, as described on pages 22 and 23, thereby receiving a completely natural appearance without any evidence of having been in a fire.Ĩ) Boiling: the copper coins also can be boiled ten minutes in solution of Baking Soda and water.ĩ) Removing Verdigris: verdigris is most easily removed by rubbing with a moist cloth which has been passed over copper soap.ġ0) Immersion into 10% Ammonia (NH4OH) Solution Bath (described on page 13): the coins should be immersed for a few minutes or continually taken out, soaked with several changes of water and brushed. The copper coins, if not too severely oxidized, appear as fresh as if they had just come from the mint. The coins are then neutralized for a short time in very dilute Sodium Hydroxide (caution: caustic soda) and are rinsed. The coins are then washed under the faucet and rubbed energetically with a copper cleaner - Vitrolin copper cleaning soap. Sweden 17th Century Dug Copper Coin Before Cleaning in Hydrogen Peroxideġ666 1/6 Ore Swedish Coin After Being in Hydrogen Peroxide Bath for One Hour and Then Patinatedħ) Copper Scale Removal: dull orange-red changes (Cu2O, cuprous oxide) and black coatings (CuO, cupric oxide) are caused by annealing of the copper coins, and have destroyed at least the coin's surface and sometimes even the whole coin.Ĭopper scale is removed by putting the coin in dilute Sulfuric acid (5% to 10%) for no longer than 10 minutes. Please see an example of treatment of a bronze Indian Head penny with a toothpick on page 8.Ģ) Cleaning with Brushes (see details on page 6).ģ) Wet Cleaning (see details on page 10).Ĥ) Cleaning with Carpenter's Glue: this method is used for dirt and false patina (see page 10).ĥ) Cleaning with Vitrinol Copper Soap (available in drugstores): the soap is applied with a moist cloth used to rub the coin.Ħ) Immersion into a Hydrogen Peroxide (H2O2) bath (described on page 11) is applied briefly to remove the dirt. The following methods can be used for cleaning copper coins:ġ) Cleaning with Soft Erasers, a Toothpick, a Bone Stylus, and Ink eraser for large amounts of the coating, which can be sandy, clayey, saline or greasy. Specifications of ALL Today's Metal DetectorsĬleaning and Preservation of Coins - A Complete Guide, page 17 HOW TO CLEAN COPPER and BRONZE COINS: Various Effective Methods and Applications
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