PRESERVATION & CONSERVATION of COINS - A Complete Guide, page 26
Useful Tips, Methods and Techniques:
1) Protection Against Sun Rays: The very harmful effect of sun rays on various materials such as paper, fabric, dye, etc. are generally known. All coin metals should also be protected from the influence of direct sun rays. They affect, in particular, the quality of polished plate, as well as die polish, which, when exposed to sunlight, becomes turbid and lusterless after a short time.
2) Separate Storage of Various Coin Metals: Various coin metals should not be stored for prolonged periods of time with one another, particularly when a certain room humidity is present. Observance of this rule is extremely important when the salt content of the air is high.
3) Lacquering Coins: Lacquering protects all coinage metals against the usual effects of air, water and soil. Lacquering can be used only for coins in collections that are touched infrequently, because with even slight abrasion, the lacquer loses its luster and the details of the coin are no longer clearly visible.
The following two methods are used for lacquering coins:
Zapon Lacquer: This lacquer is most frequently used and obtainable in every paint store. However, brush application is not recommended because the brush marks are often visible, and pores result from the air occlusions in the brush. If the coins are kept in polyvinyl chloride bags, these pores permit access of the corrosive influences of these materials.
Immersion of coins is the best method of Zapon lacquering. For this, Zapon lacquer is thinned with 50% lacquer thinner. Small clips, available in photographic equipment stores, which will not damage the coins, are attached to the coins. The clips can be hung up to dry from a wire or string.
The coins are then dipped in succession into the lacquer down to where the clip still remains clear. After the superfluous lacquer is wiped off against the glass, the coin is hung up to dry. Drying is complete in an hour. The room should be free of dust.
Then the clip is attached to the side of the coin that has the lacquer coating and therefore hung downward during drying. The coin is then immersed into the lacquer at the free end, again up to nearly the height of the clip. The lacquer then forms a smooth satisfactory surface and the division line between the two applications cannot be seen.
Nail Polish: If only one or a few coins are to be lacquered, nail polish can be used. The process is like that described above.
• Lacquering Silver Coins: Silver coins rarely need lacquering unless it is to prevent tarnishing from the action of sulfur during lengthy exhibition, such as raveling exhibition.
• Lacquering Copper Coins: Lacquering of copper is advisable because copper tarnishes very quickly.
• Lacquering Iron, Zinc and Aluminum Coins: Coins of these metals always should be lacquered to protect them from oxidation which is very harmful. These coins cannot be preserved in mint state if they come into contact with any kind of moisture.
• Lacquering Lead Coins: Lead, mostly in the form of lead reproductions, is immersed into heated beeswax or paraffin. The wax then is shaken off. The lead piece is placed on blotting paper and the wax is blown away with a conventional household fan so that only a skin layer remains which penetrates to all the pores.
4) Protection by Oils: Kerosene, like solid paraffin and Vaseline, is obtained from petroleum, wood tar and coil tar. It is a particular characteristic of these materials that they are insoluble in water and are not attacked by acids.
• Kerosene is suitable for protection of coins to a certain degree, however, it does not provide lasting protection.
• Paraffin (the name comes from "parum affinis" meaning not prone to form compounds) is not suitable because it forms a dull white film.
• Vaseline is not suitable because when applied, it forms a porous film that permits entry of air and moisture.
• Firearms Oil gives special rust protection through strong alkalinity. It can be used to protect large quantities of iron coins. Its very thin film suffices to ensure many years of rust protection.
Ballistol is the trade name of one of those coin protective oils which is available in most countries. If the oil film is to be removed, it can be rubbed off with a cloth moistened in ethyl acetate.
5) Keeping Coins in Dry Environment: Ideally, you should keep your coins in a low-humidity environment. You can place a small bag of activated charcoal or a piece of chalk in your coin cabinet to minimize future tarnish.
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