Collection and Preservation Skills of Coins In China, collecting coins has a long history. Since the reform and opening up, the popular collection of coins in the world is in the ascendant, and its status as the main collection has been recognized by more and more collectors. Due to the lack of knowledge introduction, communication and media publicity, some collectors are at a loss about the preservation of coins. It is often seen that many refined coins (proofs) were originally packed in airtight plastic, shining like mirrors, but what can be seen in the market is that they have been sealed and the mirror of the coins has disappeared, but there are many fingerprints or scratches. Some coins have been scarred beyond recognition after a period of exchange in the market. Although the coin is made of metal and has a certain hardness, it looks less likely to be damaged. In fact, it is not easy to keep coins. The appearance of coins is divided into 70 grades according to American standards. The correct preservation method should slow down or stop the corrosion process of coins, so as not to cause serious damage, and try to maintain the original appearance level.
Improper preservation often only adds a black spot with a scratch or the size of a needle hole that can be seen with a magnifying glass, which will make the coin drop by more than one grade, while a coin with a grade difference of hundreds or even thousands of dollars in Klaus' standard coin catalogue is by no means an individual. Keeping coins properly not only protects your collection, but also protects your assets. On the other hand, it is also to preserve the historical heritage for the next generation of society.
In order to preserve coins, let's start with the deterioration of appearance. The corrosion process of coins depends on the following factors: chemical stability (composition) of coin materials, materials in contact with coins for packaging, atmospheric conditions for storing coins and contact observation of coins. Generally speaking, gold is more resistant to corrosion than silver; Silver is more resistant to corrosion than copper; Metals such as zinc, aluminum and iron are easily corroded. For alloys, sometimes it depends on metals with more active chemical properties, such as pure gold, which has better stability. When copper is added to gold to form an alloy, coins are prone to black spots. But brass (copper-zinc alloy) is more corrosion-resistant than pure copper in the atmosphere. PVC in packaging materials is harmful to coins. At room temperature, PVC will gradually precipitate plasticizer to corrode coins, which will cause irreparable losses. We should pay enough attention to this, especially copper and copper alloy coins. In foreign countries, the harm of using PVC has been widely recognized as early as the early 1980 s, and this material has been eliminated in the packaging of coins and replaced by polyethylene. Water vapor, sulfide, carbon dioxide and other substances in the air are also very harmful to coins. For example, sulfur reacts with silver to produce silver sulfide, which turns the surface of silver coins gray and black. Moisture in the air will also accelerate the oxidation process of coins. In the process of appreciation, touch the bare coin with your hand and let the sweat leave fingerprints on the coin; Saliva and dust in the air fall on coins, and these attachments will accelerate the corrosion process of coins.
If you want to keep coins well, you must first choose a good packaging method, which is not only convenient for viewing, but also conducive to protecting coins, depending on your personal situation. Optional packaging includes plastic boxes other than PVC, polyester film circular hole paper clips, polyester film bags, paper bags and so on. Optional materials are polyethylene, polypropylene and polyester film. For the convenience of appreciation, it can also be put into the coin collection book on the basis of transparent packaging. The key is that you can't choose materials containing PVC to package and store coins, and its harm can't be underestimated. In order to isolate the air, there are generally two methods: closed and vacuum packaging. Air tightness refers to isolating the air, not pumping out the air in the package. Vacuum packaging will bring the packaging material into close contact with the coin surface, which may also damage the coin. Packaging adopts thermoplastic compression or ultrasonic welding, which has not been popularized, and is generally only used to package new coins of mint and graded coins of rating agencies. The easiest way to isolate the air is to soak coins in anhydrous alcohol. The disadvantage of this method is not easy to see, but the effect is good. Coins should be stored in a ventilated, clean and dry place.
Generally speaking, don't play with bare coins directly, especially don't touch refined coins, uncut coins or advanced coins. The place where the hand touches the coin must be the first place to corrode and turn black. If you really want to take and put coins, separate the edges of the coins with clean soft paper or cloth.
Coins generally don't need to be cleaned, especially they can't be wiped with ordinary rubber or glass fiber wiping rods sold in the market, which will scratch the surface of coins. If there is green mucus on the surface of the coin after packaging with harmful substances, it can be cleaned with anhydrous alcohol. For stains and fingerprints on coins, alcohol can also be used to clean them, which is effective for new traces and can prevent further erosion of coins by stains and fingerprints. For old traces, if necessary, you can wipe them properly with high-grade drawing glue without sand. For coins with large dirt and especially dirty, ultrasonic cleaning machine can be used if conditions permit, and alcohol should be used as cleaning liquid at this time. Coins should be suspended in the cleaning solution with mesh bags to prevent coins from directly contacting the inner wall of the cleaning machine and causing damage, because mechanical vibration of the inner wall and collision of coins will damage coins. This will remove dirt without scraping coins. It should be noted that cleaning can not improve the grade of coins, but is beneficial to viewing (removing excess substances attached to coins). The grade of a coin depends only on the degree of wear and tear of the coin itself.
Coin collection method 1. Precious coins should be packed in a package. Gold and silver coins are soft and easy to be damaged due to mutual friction, and the most prominent part of the relief is also the easiest to be scratched, so gold and silver coins should be packaged in one piece. Precious ancient money should be like this.
2. Precious metal coins will be bruised when they fall on the ground or touch hard objects, while ancient coins are mostly rusted and may be broken when they fall on the ground. Excessive force can also cause fracture and breakage, so be especially careful about this ancient money with serious corrosion.
3. The surface of ancient coins will generally form protective rust. This kind of protective rust is also called old rust. Rust is hard, green, blue and red. It can protect itself and cannot be destroyed.
4. Qian Wen produced by corrosion can be soaked in strong acids such as edible vinegar and sulfuric acid. When soaking, turn it over at any time to observe that enough is enough, then wash it with water and a soft brush and dry it. Under normal circumstances, it is best not to use physical means to remove rust from ancient coins, otherwise even if they are cleaned, their appearance will be destroyed. Iron coins are easier to oxidize than copper coins, so we should pay more attention to protect the rust on the surface of iron coins, including the ancient colors handed down from generation to generation, otherwise it will only promote their corrosion and get the opposite effect.
5. Gold and silver coins often darken due to long-term oxidation, which affects the appreciation. You can soak them in a small amount of special cleaning solution and then rinse them with clean water.
6. Harmful rust will make money rot quickly and be contagious. Harmful rust is powdery, and coins with harmful rust should be isolated immediately.
7. The collection of coins should be kept by age and category, because different textures have different requirements for temperature and humidity. It can be classified by drawer-type cash boxes, or stored separately by different coin books or plate-type coin boxes. Dry it before entering Tibet to avoid being touched by sweaty hands. Coin cabinets, boxes and books should be kept in a dry and dark place to avoid rusting due to moisture. Paper money should also be prevented from pollution such as oil pollution, and attention should be paid to mildew and moth prevention. In summer, especially after the rainy season in the south, you should see the sun at least once a year.
8. As for the baby, the money should be stored separately to avoid being mixed with ordinary products. The difference between some treasures and ordinary products is only subtle. Special brocade box, velvet box or mahogany box frame can be made, and celebrity inscriptions are added to make it more elegant and luxurious.
The collection and preservation method of paper money should be kept in PVC plastic bags, and it is PVCJUYI that has passed international testing. If the quality of PVC plastic bags is not up to standard, paper money will darken and change color when placed inside. When reading, you must pick up the paper money with tweezers to avoid the injury of sweat stains on your hands.
There are many things to pay attention to when storing paper money, which can be summarized as four points, namely, prevention? Mildew? , defense? Fold? , defense? Moth? , defense? Fade? .
? Mildew? That is, the key to mildew prevention is moistureproof, which is particularly important in the south and coastal areas. The key point of moistureproof is the temperature and humidity of paper money. The optimum indoor temperature for paper money storage is 18 to 20 degrees, and the humidity (relative humidity) is 50 to 60 degrees. Try not to dispose of the collection in the hot and humid environment in summer. Generally speaking, old paper money is more prone to mildew than new paper money. Once moldy, you can gently wipe it with soft paper and cloth. For paper money with serious mildew, you can soak it in fresh milk, soak it in a little salt for one hour, then take it out, rinse it with clear water and blot it with absorbent paper. When it is slightly wet, I will put the paper money flat in a white book and flatten it with a heavy object.
? Fold? That is, it is forbidden to touch or twist brand-new banknotes by hand. Because there is oil and sweat on your hands, it is easy to pollute the surface of coins. Use a camera when looking at pictures, and it's best to put paper money in the coin collection book. For paper money with a light Microsoft fold, put it flat in the book, press a heavy object, and it will be flat in a few days. However, banknotes with obvious hard folds are generally dirty and can be washed and dried with clear water. Don't wash paper money printed on tissue paper, because it will easily damage the printed surface and make it blurred. For uneven paper money, avoid ironing with an electric iron, because it is easy to hurt the paper.
? Moth? That is to say, preventing insects from eating is to keep paper money dry and ventilated. For long-term preservation of banknotes, they should be read regularly every year. One is to play the role of ventilation, and the other is to check whether the collection has changed. Never pile up paper money with newspapers, books and other sundries. Worm-eaten paper money should be framed and repaired.
? Fade? That is, the key to prevent paper money from fading is to avoid paper money being exposed to the sun. Paper money will fade in different degrees after being stored for a long time, which is directly related to the quality of paper money and ink. Paper money should not be washed with alkaline or acidic liquid, otherwise it will fade easily. Generally, paper money should not be put in glass paper bags, and it is easy to fade. Once the paper money fades, it is irreversible.