Preservation takes many forms.
Helium-filled encasements framed in pure titanium are used to preserve the Declaration of Independence, the Constitution and the Bill of Rights. Helium-filled encasements used to preserve documents may not be the first preservation choice for local government records keepers but other protection methods are available at more reasonable costs. Encapsulation is a process developed and tested by the Library of Congress to protect fragile and brittle papers. It involves placing sheets of a document between two clear sheets of polyester film and sealing the film to itself, not to the document. The film is sealed around the edge with narrow, double-stick tape, or by machines designed to bond the film.