[PADG:590] Postcard enclosures

["Patricia P. Selinger" <patricia.selinger@xxxxxxx>]

I could use your help with this question. Is there an "archival" form of 
PVC? I've searched the Conservation DistList archives with no result. We 
don't have a fume hood for chemical tests. These are rigid plastic 
enclosures for our postcard collection.


Patricia,

	We purchased some 16 mil rigid plastic loaders to house our
historic postcards. The ad says they are: "Archival quality:  acid-free,
contains no plasticizers or stearates. Made from high impact grade PVC
that is 100% non-migrating."
	I had always been taught that PVC was very bad from an archival
standpoint because the plasticizers would create 'off-gas' that would
migrate onto the paper rapidly aging it while making the PVC very brittle.
But in researching this I'm finding other products (from medical supplies
to roofing materials) that claim to be PVC with either no plasticizers or
non-migrating plasticizers. Among these are a number of products designed
to hold baseball cards or comic books that make similar claims to those
above.
	I did a simple sniff test that was recommended by several people
on the archivists listserve. They said that PVC has a 'new car smell' and
that indicates that there is off-gas. These did not have any smell even
though they were fresh out of the packaging.
	So my question is, is this a truly archivally safe form of PVC? We
haven't been able to find any known archivally safe plastic products
thicker than 5 mil, so if these are safe then they are what we would want
to use. But this is a valuable collection, so we can't take any chances
with it.

				Curtis Lyons
				VCU Libraries



--
Patricia Palmer Selinger
Head, Preservation Department
Virginia Commonwealth University Libraries

patricia.selinger@xxxxxxx
(ph)   804.828.1096
(fax)  804.828.0151