The Problem of Plastic
Plastic, 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.