The Problem of PlasticPlastic, like all organic materials, can deteriorate in a variety of ways. Thi
The Problem of PlasticPlastic, like all organic materials, can deteriorate in a variety of ways. This degradation can cause changes to its appearance and physical properties. Deteriorating plastics are found occasionally in the Official Military Personnel Files held in St. Louis when plasticized identification cards were kept with the record. Some plastics, like this Navy ID card, shrink as they age. The photo inside the plastic has been forced into a severely confined space over the years as its plastic housing has contracted. Although physically distorted, the photograph itself is chemically stable. Once free of the plastic, the photo ID only needs to be relaxed with gentle humidification to become flat again.Another ID card issued to a Marine was laminated in a plastic that became sticky over time and oozed out of the card making the edges sticky. At some point, it was placed into a plastic zip bag used by the Navy as a “document envelope” in order to contain the sticky deterioration. This plastic envelope also deteriorated, yellowing and contracting. Inside, the entire bag became one sticky mess. The original plastic laminated card has been removed from the plastic envelope and is now housed in a polyester sleeve meeting archival specifications. Unlike the “document envelope” we found the card in, this sleeve is stable. (Those plastic sleeves you buy at the office supply store may also be polyester, but they contain additives and slip agents that make them more attractive products so that they are clear and paper can slide in easily—but can deteriorate over time.)For laminated paper, additional conservation treatment are available but are time-consuming. Although readable as it is, the paper has become translucent due to the laminate’s adhesives and will continue to deteriorate inside the laminate card. Since we do not have the resources to do further treatment for this ID, we have made a preservation photocopy for the file and will keep the original card in its new sleeve in the record. -- source link
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