Polyester welding machines

Harlan M. Greene <ncpc<-a t->mindspring< . >com> writes

>Does anyone have any experience with the fairly inexpensive
>heat-welding polyester machines in some archival catalogues? Are you
>aware of any studies or literature on the effect on paper items
>sealed into such envelopes by heat?

As both a manufacturer of polyester (mylar/melinex) enclosures and
sealing machines (heat bead welders) and a distributor of
ultra-sonic units I would like to clarify something Harlan Greene
has referred to in the enquiry on the sealing of ephemeral material
in heat welded enclosures.

Our experience is that people rarely using heat welders to fully
encapsulate the material they wish to protect. Most of the people we
know prefer the enclosures they use to have three sides sealed or
even just the one or two sides sealed. Certainly the consensus of
opinion is towards an opening on at least one edge.

Air should be able to circulate within the mylar or melinex
enclosure, fourth edge sealing or full encapsulation (particularly
when one is leaving air in the pocket) may raise the possibility of
damage from microcultures forming within the sealed unit.

Polyester sealing machines are designed to make bespoke enclosures
from polyester and/or associated heat welded material. Used properly
they form another useful accessory for the conservators workshop and
enable collections to produce their own protective storage products
to enhance the lifespan of material in the collection.

Mark Vine
Conservation Resources
England

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                  Conservation DistList Instance 11:7
                  Distributed: Wednesday, July 9, 1997
                        Message Id: cdl-11-7-011
                                  ***