Polyester encapsulation is a safe and economical way to house historic documents. It provides a light weight enclosure which allows you to view and handle objects without touching them directly. This helps keep the documents or photographs soil free and prevents the transfer of finger prints that can discolor your material and cause photographic images to fade.
Encapsulation requires the use of two sheets of archival quality polyester film, Melinex 516 or Mylar D, which are ultrasonically welded around the perimeter of the object. This differs greatly from the lamination process where the plastic film is directly adhered to the artifact. An encapsulated object can be extracted from its enclosure at any time simply by breaking the weld and removing it from the polyester sleeve. The object is not adhered to the polyester film. Plastic films that are safe to use with objects of historic value are polyester, polyethylene and polypropylene. Polyester is the most stable of the three. Polyvinyl chloride (PVC) plastics are unstable and should never be used. Encapsulation is not appropriate for objects with friable media such as pastels or charcoal drawings.
Encapsulation is ideal for brittle books with very weak leaves that are difficult to handle such as record books. Book leaves can be encapsulated with the lower polyester sheet forming a binding tab then post-bound or thin books and pamphlets can be side-sewn into a binder.
ECS Conservation has a Minter ultrasonic welder at each of its locations at its disposal for encapsulation. Our large format welder in North Carolina can seal an object up to 64″ in length with a single continuous weld per side. ECS Conservation stocks polyester film in 3 mil and 4 mil.