Then the coin with brown-yellowish film is brushed with the solution 2, twice a day for 4-5 days, followed by rinsing with cold water each time. Solution 2 is prepared by dissolving 50g of Copper Sulphate 5-hydrat (CuSO45H2O), 10g of Sodium Hydroxide (NaOH, also known as lye or caustic soda) and 176g of Ammonium Hydroxide (NH4OH) in 1 liter of water.įirst, the coin's surface is washed by the solution 1 two or three times, followed by rinsing and drying each time. Solution 1 is prepared by dissolving 100g of Ammonium Sulphate ((NH4)2SO4) in 1 liter of water. The resulting patina is strong and resistant to corrosion. The coins are immersed into this solution, heated up to 149☏ (65☌), for 10-15 minutes. This method is illustrated in my tutorial - Simplified and Quick Method for Cleaning Copper Coins and Enhancing Their Designs' Appearance.ĥ0-70 g of Potassium Chlorate (KClO3), 40-50 g of Cupric Nitrate "Trihydrate" (Cu(NO3)2) and 80-100 g of Ammonium Chloride (NH4Cl) are dissolved in 1 litre of water. If the coin is boiled in this solution for more than 10 minutes, it gets a black-violet patina.Īppearance of Black-Violet Patina when Coin is Boiled Excessively The surface can be polished with a soft cloth or special coin polishing cloth with anti-tarnish protection. The coin is left for 24 hours, then rinsed with hot water and dried. The solution is applied with a brush to the coin. 20 grams of Copper Sulphate Pentahydrate (CuSO4♵H2O) and 5 grams of Potassium Permanganate (KMnO4) are dissolved in 1 liter of water of the room's temperature. This patina has a gold-like brown color with a slight tone of pink and a moderate luster. The following methods, not widely known, are used for patinating copper, bronze and brass coins in nine desirable colors: As for artificial patination, use of various soluble mixtures of these sulfur-containing compounds with other substances allows to patinate coins in a number of colors that are characteristic for aged copper. Generally the sulfur-containing compounds are used for tarnishing the copper-base alloyed coins and relics.
However, these organic coatings do not last long, and after their disintegration begins, new centers of the unequally changing patina appear. That is why a great care must be exercised here.Īrtificial patinas are not stable under the influence of air and, therefore, should be protected by the lacquer, wax or oils. NOTE: Before the patination, the coin metal surface must be degreased, thoroughly washed and dried.ĭuring the process of patination, the patinating solution slightly smoothes the coin's micro relief by dissolving the surface layer of the coin's metal which is replaced with a thin film of cuprous oxide. Both true patina and artificial patina protect the copper and copper alloys against the external influences, and give the copper coins and relics aesthetic appearance. True patina and its origin are described on page 3.
GOLD PATINA COLOR HOW TO
Cleaning and Preservation of Coins - A Complete Guide, page 23 ARTIFICIAL PATINATION of COPPER, ZINC and IRON COINS HOW TO PATINATE COPPER COINS in 9 Desirable Color Tones
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