There are several reasons to prefer Mylar® film over all the other commercially available choices. Here are five major reasons:Mylar® is chemically inert; it will not react with paper or ink. Many old documents were printed or written on acidic paper and some inks were very acidic as well. Some other plastic films, notably PVC, or Polyvinyl Chloride, will react unfavorably with such items.
PVC continually out-gasses vinyl chloride, which combines readily with moisture in the atmosphere to produce hydrochloric acid. This can be quite destructive to an old document, especially when confined to a plastic pouch or holder, in a box, drawer, or album.
Mylar® is an effective barrier to contamination; it will neither allow contamination to pass through it, nor will it allow contamination to be absorbed. There are no manufacturing chemical residues in or on Mylar® film to harm your paper collectibles.
Mylar® film is crystal clear, allowing your items to be viewed in their holders; there is no need to remove them for inspection, risking degradation or damage. No other plastic film makes your material look better than Mylar®.
Mylar® won't stick to your items, not even photographs. There is no risk to any contemporary, or historic, photographic medium.
Mylar® is a registered TradeMark of the DuPont Corporation, for their archival polyester film. The impressive reputation of DuPont's Mylar® film has also resulted in the word Mylar being used as encompassing all archival films. In fact, the only other (at the time) manufacturer of archival polyester film, ICI, maker of Melinex 516, was bought by DuPont a few years ago. Since then, DuPont has closed the original Mylar manufacturing plant, continuing to make its archival polyester film at its Mellinex facility.
The two products were and are indistinguishable; indeed for many years the Library of Congress has recognized only these two products, Mylar TypeD, and Mellinex 516, as being safe for archival storage. We will settle for no less.
