Archival Characteristics of Plastics

"Plastics vary greatly in chemical stability and should be used with caution. Some plastics are unstable chemically and produce by-products as they deteriorate that accelerate the breakdown of paper. Others contain volatile plasticizers that can cause items in contact with them to stick to their surface and media to bleed. Three types of plastic meet preservation standards: polypropylene, polyester, and polyethylene", states Gary Albright of the Northeast Document Conservation Center in a technical leaflet entitled "Storage Enclosures for Photographic Materials". (5)

Plastic Terms & Definitions:

Polyester: An inert, highly stable, and rigid plastic considered safe for preservation applications. However, it is an expensive material and can generate static electricity. This static electricity can adversely affect photographic images and can attract dust. It is not recommended that polyester is used in direct contact with photographs or loosely bound media such as pastels, chalk, charcoal, and soft graphite pencil. Polyester is most appropriately used for preservation purposes in the form of folders and encapsulation. (4, 5)

Polyethylene: Compared to polypropylene and polyester, polyethylene is the most easily marred and least rigid of these plastics. High-density polyethylene is a translucent, milky plastic which is naturally slippery. Due to its transparent nature and flexibility, high-density polyethylene is often used to create clear page protectors that are considered archival quality. Page protectors made of a combination of polyethylene and polypropylene provide the best balance of safety and affordability while maintaining crystal clear clarity. (4, 5)

Polypropylene: A stiff, heat resistant, chemically stable plastic. Polypropylene can be used for the storage of photographs and other archival materials without adverse effects. Common uses in preservation are document containers and sleeves for photographs, slides or films. Polypropylene has better clarity than polyethylene and less static charge than polyester. (1, 3, 4)

Polyvinyl Chloride (PVC): Plastic enclosures made from polyvinyl chloride (PVC) are unacceptable for archival photographic storage. This plastic, often referred to as "vinyl" by suppliers, is not chemically stable and will cause deterioration of a photograph over time. PVC can emit hydrochloric acid as it deteriorates, which can damage photographs and other materials. (2, 4, 5)

Vinyl: The word vinyl is imprecisely used to refer to any of a number of plastics, many of which are not appropriate for use in preservation. PVC is often referred to as "vinyl". (1, 5)

Bibliography. The above information was compiled and/or paraphrased from the following sources, with the intention of respecting all applicable copyrights:

  1. Archival Methods (glossary section of "Archivery",
  2. Archival Supplies (
  3. Behavioral Images, Incorporated (glossary section,
  4. Icon Distribution ("Archival Safe Storage" section,
  5. Northeast Document Conservation Center (Technical Leaflet- "Storage and Handling", section 4, leaflet 11: "Storage Procedures for Photographic Materials";