Moisture is a major source of trouble for magnetic (tapes, cassettes) and photographic media alike. While virtually all photosensitive materials deteriorate with age, the rate is largely dependent upon the ambient weather. Deterioration increases rapidly under high temperature and humidity levels. High humidity alone is usually more harmful than high temperatures.
Humidity is a natural enemy of storage and preservation of tape and magnetic media, and can result in loss of readable data because of decreased magnetic capability and deterioration of the binder/ backing of the tape. The moisture menace is elevated during the monsoons when the moisture content in the storage area is alarmingly high. In the presence of humidity, mould and fungus grow, and also cause hydrolysis which causes binder breakdown of magnetic media. Many kinds of fungi, including Alternaria, Aspergillus, Epicoccum, Paecilomyces, Penicillium, and Trichoderma on the diskettes foul the device by causing binder breakdown. Fungus growth is more prominent in silver gelatin films. It is necessary to block the fungus growth in its tracks before it makes a permanent impairment. They have to be stored in low and stable temperature and humidity conditions. Dust also should be prevented from entering the storage areas. When materials absorb moisture, they cause degeneration and provide a base for micro-organisms to multiply and breed causing irreparable damage.
Varying levels of humidity are even more dangerous, causing condensation and creating moisture, which is trapped inside the tubes.
General Recommendations
Dehumidification is essential in the preservation of rare objects, photosensitive material and magnetic media.
A desiccant dehumidifier with cooling coils is the most effective and economical way of achieving the desired conditions. It is recommended that the medium to be stored at:
- Master film based records: 5°C-12°C (41°F-54°F) at 30%-40% RH
- Magnetic media: 18°C-20°C (64°F-75°F) , at 35%-40%
- Optical disks: 4°C-20°C (39°F-75°F) at 20%-50% RH
Bry-Air Solution
Bry-Air Desiccant Dehumidifiers, when used in conjunction with air conditioning, can provide the perfect environmental storage conditions for all sorts of valuable photosensitive materials, magnetic media, artifacts, documents and works of art. Bry-Air Dehumidifiers provide a low humidity environment which prevents microbial attack.
For storage and preservation, archives and libraries should maintain humidity levels of 40-45% RH. This level of humidity prevents drying out of the material. Simultaneously, it also prevents warping and the formation of mold.
- Negative films to be stored at temperatures of 13°C-20°C (55°F-70°F) and a relative humidity of 30%
- Video tapes to be stored at temperatures maximum of 15°C (59°F) and 25%-35% relative humidity
Some References
Bry-Air has installed many Dehumidifiers to maintain the ideal conditions in archives, libraries for books/ document preservation, microfilms, video and audio tape storage
- Namgyal Monastery Video Lab. Dharmshala, India
- National Photo Library, Malaysia
- Philippines T.V. Station, Philippines
- Radio & T.V. Malaysia (RTM)
- Republic Broadcasting System (TV Station), Malaysia
- Satyajit Ray Film & TV Institute, India
- All India Radio, India …and many more
