Philatelists Have to Know: the Selection of Postage Pouches
When collecting stamps, you don't pay special attention to the protection of stamps. Without any protective equipment, you can take the stamps with your hands at will, which damages many precious stamps. Later, I learned that there is a special postage bag, which is what we are talking about now. There are many types of protective mail bags. According to the material, they can be roughly divided into four types: cellophane, polyvinyl chloride (PVC), polyethylene (PE), and polypropylene (OPP).
Faced with a dazzling array of products, how should we choose a protective postage pouch? What kind of protective postage pouch will not damage the beloved stamp?
Cellophane is the earliest type of mail tamper proof bags, and it has been basically eliminated. This is a kind of transparent cellulose film called cellophane. It feels good at first, but it has two disadvantages that are particularly fatal to stamps: moisture absorption and aging. If the weather is damp when you are wrapping, when the weather is dry, the film shrinks and the size becomes shorter, and the stamp will wrinkle; after severe moisture absorption, especially when the black backing paper is wrapped with the stamp, the stamp will still be moldy; After a few years, the film tends to become brittle and cause cracks.
The PVC postage pouch overcomes the shortcomings of cellophane, but has strong "adhesion" to the ink. This type of postage pouch will absorb the ink of the stamp after a long time. After a longer time, the color of the stamp screen will be "printed". The above, especially the gold on the stamps, quickly made it dull and damaged the appearance of the stamps. In addition, this material is also toxic, so it is not recommended.
PE mail postage pouches are more common in the market at present. Compared with PVC, they are non-toxic, but the transparency is not good. The finished film on the market is generally thinner, and it is easy to wrinkle when wrapped with a soldering iron, such as double-sided adhesive The film is easy to tear or deform when it is pasted and then removed and reposted. This kind of protective mail bag is reasonably priced and can store ordinary stamps and short-term use, but it is recommended to replace it after a few years.
0PP is the most effective mail postage pouch at present. It is non-toxic and has significantly stronger transparency than PVC and PE. It has high strength, no moisture absorption, and the film is stiff and flat. Due to the high melting temperature, it is not easy to wrinkle when heated with a soldering iron. At present, the most ideal material is suitable for protecting high-end stamps and long-term protection of stamps, but the price is higher, generally twice that of ordinary PE materials, but it is definitely worth the money.