The idea of not completely sealing paper items in plastic enclosures came from research that the Library of Congress undertook in the late 70s/early80s. Their research showed that acidic paper deteriorated more rapidly if completely encapsulated (ie. no gaps) than unencapsulated paper, hence the recommendation that paper be deacidified before encapsulating and that gaps be left at the corners of the encapsulate. However from the point of disaster prevention (potential water damage) it is preferable to seal objects completely in archival quality enclosures. Tamara Lavrencic Collections Manager Historic Houses Trust of New South Wales