Often coins that get to collectors have a shabby appearance - corrosion spots, dirt, darkened metal. When creating a collection, a good numismatist will never leave dirty or oxidized samples in it. What is the way to restore the quality of old coins?
Instructions
Step 1
Determine the alloy the coin is made of. Different types of alloys are characterized by different types of oxidation, which have to be dealt with in different ways. Common to all types of alloys is the method of cleaning coins from dirt and dust. It is necessary to rinse the coin in warm running water using a toothbrush or soft brush. Use the same technology to clean the gold coin, after putting it in the soap gruel.
Step 2
Before cleaning silver coins, determine the sample of the silver from which it is made. If the silver is below 625, use plain lemon juice to clean it. The coin is completely immersed in the solution and should not be in contact with air. Otherwise, its oxidation may occur at the interface. Then you need to rinse the coin with running water. If the silver is higher than 625, use ammonia. It will well remove dirt and plaque from the surface of the coin.
Step 3
Copper coins are cleaned by immersing them in a soapy solution. This is the safest method for copper alloy and avoids damage to it. Remember to remove the coins from the solution and rinse them under running water, cleaning them with a soft brush. It is also effective to use table vinegar for purifying copper (acetic acid content 5-10%). If the coin is not strongly oxidized, its residence time in the solution should not exceed a couple of minutes. In case of strong oxidation, leave it in the solution for several hours. Flip coins in the solution to speed up the chemical reaction and cleanse more effectively.
Step 4
Coins made of zinc-iron alloy are cleaned with a weak solution of hydrochloric acid, followed by a brush with stiff bristles. Use a needle or other sharp object to remove any signs of rust and deposits. Dip the coin in a weak solution of hydrochloric acid and keep it under constant supervision. After the rust and oxides have melted, rinse it in warm running water and wipe with a felt.
