Long-Term Microfilm Storage Tips for Archive Vaults

Visits to archive vaults have shown that certain problems and misconceptions repeatedly put vital records at risk. This guide summarizes standards requirements and common mistakes to keep information permanent.

Highlights

• The original camera negative of permanent records should never be used for reference and must be stored in a fire-resistant vault (ANSI/AIIM MS48-1990 section 7.1)
• For reference, make a limited number of working copies on Diazo, Vesicular or Silver film
• Relative humidity no more than 40 percent and temperature no more than 70º F, with variation of less than 5 percent RH or 5º F in 24 hours (MS48-1990 section 8.4)
• Diazo and Vesicular films should not be stored in the same cabinet as silver films (MS23-1998 section 15.6)
• Inspect master films annually to detect chemical deterioration early (MS23-1998 section 16)

Sources of airborne oxidants

Under ANSI/AIIM MS23-1998 section 15.4, oxidants are the main cause of microblemish (redox) formation on silver microfilm. Common sources:

• Ozone from copiers and fresh oil-based paint
• Cleaning agents, construction adhesives and cosmetics
• Engine exhaust fumes
• Deteriorating paper and low-quality cellulose products, including acetate film with vinegar syndrome
• Adhesive tape, rubber bands, ink, glue and textiles

Common problems in storage vaults

• HVAC system with insufficient capacity and filters not changed monthly
• Boxes stored in unsuitable enclosures (cardboard, wood, metal and plastic) or boxes without Acid & Lignin Free certification
• Incorrect settings and fluctuating temperature and humidity
• Plywood-paneled walls, carpeted floors and fresh painting without removing the film
• No air exchange and no positive pressure
• Contaminated film or Diazo stored next to fresh silver film
• Cabinets less than 6 inches above the floor
• Dirty environment, signs of insects and rodents, and mold growth
• No fire suppression system and untrained staff
• Molecular Sieves not used in every roll
• No polysulfide treatment such as Kodak Brown Toner
• Non-silver copies kept instead of masters, and masters used for reference

Reference standard

ISO 18911:2000(E) section 7 requires that the temperature and humidity conditions recommended in Table 1 of the standard be maintained inside the storage enclosures or rooms.