The older the coin is, the more time is visible on it: dirt, corrosion, discoloration of the metal. This is especially true of ancient specimens that have lain in the ground for tens, and sometimes hundreds of years. For further storage or sale, the coin must be cleaned of dirt that spoils its appearance.
It is necessary
Distilled water, toothbrush, soap, soft felt, ammonia, baking soda, lemon juice, vinegar
Instructions
Step 1
There are three main ways to clean coins: chemical, mechanical and electrochemical. Mechanical processing consists in the use of various brushes and needles. In this case, it is very important not to spoil the surface of the coin by accidental scratches and not to damage the details of the drawing. Most often, when cleaning and restoring coins, a mechanical method is used in combination with others.
Step 2
Start cleaning the coin by removing dirt and dust particles. To soak the dirt, immerse the coin in distilled or at least bottled water. It is better not to use tap water, as it contains chlorine and corrosive calcium and magnesium salts. When dirt starts to separate easily from the coin, brush it thoroughly under running water using a toothbrush and soap. This method is suitable for all coins.
Step 3
Gold and platinum coins generally require little maintenance other than removing grease and dirt. To do this, moisten medical cotton wool with alcohol or acetone and gently wipe the coin.
Step 4
To remove traces of oxidation, you need to know from which alloy the coin is minted. Depending on the type of metal, one or another cleaning method is selected. Fully immerse silver coins made from alloys below 625 in a container of lemon juice. Make sure that when the coin is in this solution, there are no areas of contact with air on its surface. Otherwise, side oxides may form. Flip the coin periodically. Oxidation traces should gradually disappear, then rinse the coin in warm water, wipe with a soft cloth and dry.
Step 5
For silver coins of a higher standard, use a 10% solution of ammonia. If you don't know the fineness of silver, simply wipe the surface of the coin with baking soda gruel and a little water. This method is not always effective, but it is suitable for all silver alloys.
Step 6
The greatest challenge is the fight against oxidation on copper coins. Submerge the coin in a 5-10% vinegar solution for 24-48 hours. From time to time remove the copper coin from the solution and carry out a mechanical cleaning, removing the softened layers with a brass brush. Then rinse the cleaned sample in several portions of boiling distilled water. After thoroughly drying, the copper coin must be covered with a protective layer of varnish or paraffin. The same cleaning method applies to bronze coins.
Step 7
First clean iron and zinc coins mechanically using a needle to gently remove rust and deposits. To deal with deep corrosion, dip the coin in a mild hydrochloric acid solution. Be careful with the concentration of the solution, otherwise you will hopelessly ruin the coin. When the rust and oxidation traces dissolve, wash the coin in warm soapy water and wipe with a soft felt.
