Preservation Resources, a division of OCLC, now offers a comprehensive program for protecting microfilm. It will duplicate acetate film onto a polyester base and apply polysulfide, provide polysulfide treatment or silver microfilm, or sell SilverLock to a library to treat its film.
Cellulose acetate base microfilm was produced and used for library applications for 50 years beginning in the 1920s and was particularly popular in the 1930s and 1940s. Acetate film is highly susceptible to deterioration, especially when stored improperly. The deterioration is commonly described as 'vinegar syndrome," as the slow chemical decomposition produces the odor of vinegar. By the time the odor is evident, the only solution is reduplication onto polyester film, which must be done before the film becomes so deteriorated that the legibility of the images is compromised.
Polysulfiding is the application of SilverLock to silver microfilm to protect it from redox and atmospheric pollutants. SilverLock was initially developed by the Image Permanence Institute, but it stopped making the product in 1997. Production has been taken over by Preservation Resources.
SilverLock polysulfide treatment converts most of the silver in the film emulsion of silver halide microfilm to silver sulfide, which is more resistant to contaminants. The treatment can be applied to masters, print masters, and service copies. The need became apparent in the 1980s when red spots or redox blemishes were identified in microfilm collections. Silver film produced in the last ten years can be treated with polysulfide, provided that it does not exhibit signs of oxidative attack. Research is still underway on treatment of film that is older than ten years or already subject to oxidative attack.
Preservation Resources will sell SilverLock to libraries which wish to apply it themselves. It also provides services to inspect stored microfilm on location.
Libraries concerned as much with access as preservation may wish to avail themselves of Preservation Resources' digitizing service. The organization has two SunRise SRI-50 scanners capable of scanning microfilm at a rate of 10 to 20 pages per minute. A typical reel requires four to six hours, but requires attention only 20 percent of the time, thus holding down costs. Preservation Resources has scanned over 1.4 million images since late 1995. [Contact: Preservation Resources, URL www.oclc.org/presres].
