Desiccant is a kind of dehydrating agent which absorbs moisture from the atmosphere. Its drying principle is to absorb water molecules into its own structure by physical means or to change its chemical structure by chemical means to another substance.
Examples of typical desiccant applications
How to Use Moisture-proof Beads to Preserve Photos
Everyone will find that color photographs fade after a period of time. What is the reason for their fading? One of the main reasons is temperature.
The William Institute of Image Studies in the United States has concluded that every eight years the color will fade 10% at room temperature of 24 degrees Celsius after a good photo printing process. If the color fades at 7 degrees Celsius, it takes 75 years to fade 10; 160 years to fade 10 at 2 degrees Celsius; and 2700 years to fade 10 at 18 degrees Celsius. Not only color photographs, color negatives, color slides, color film, black-and-white negatives, black-and-white slides, black-and-white film, black-and-white photographs, audio-visual tapes, VCD, DVD, computer disks, and all paper documents can be saved to -18 degrees Celsius at 20-30 relative humidity. Less than several thousand years.
The John F. Kennedy Library preserves cultural heritage in the United States using - 18 degrees Celsius cryogenic technology. Colour film came into people's social and cultural life during President Kennedy's period. Colour film was very unstable and faded very quickly. When these color film entered the cryogenic storage, it had lost more than 10 colors. At present, in addition to a large number of photo negatives, there are more than 6000 film films in the library refrigeration warehouse. The National Aeronautics and Space Administration (NASA) has built its own cold storage. In the 1970s, the China Film Archives built a refrigeration warehouse, and then built a refrigeration warehouse of more than 4,000 square meters. The Xinhua News Agency Archives has its own photo and negative refrigeration warehouse, which holds more than 1 million photo materials. In 1985, Dave Wexler, a former film producer, privately invested in a large cultural preservation freezer in Hollywood, which not only controlled temperature and relative humidity, but also installed air filtration systems and automatic fire extinguishing systems. It provides rental services for film companies, television companies, audio and video companies, music companies, museums and archives. The refrigeratory rents space for 2,400 videotapes at a temperature of 7 degrees Celsius and a relative humidity of 25 for a monthly rent of $1,550. A monthly rent of $550 is required for 120 film films at 18 degrees Celsius and 25 relative temperatures.
Is it feasible to use digital technology to make data into CD-ROM for permanent storage? First, the clarity achieved by digital means of current technology is far lower than that of the original data. Second, the way it is used has changed. Third, it is impossible to convert photographic data into digital storage. Fourth, the production cost and time are too high.
Ordinary people can adopt the method of "ordinary refrigerator + desiccant + polyethylene plastic bag seal" if they want to keep any photographic materials for a long time.