[NHCOLL-L:2999] Re: Sintra PVC archival attributes

[Victoria Book]

New products can be very confusing especially because of archival claims
(and acid-free is not the same as safe).  A good thing to remember is that
what may be totally archival and safe now (or even for many other coating
products, 4 weeks after application), may become less safe over time, as
they age.  All PVC products are like this.

If this were a short-term exhibit (a year or so) with fossil material,
Sintra would probably be okay.  For longer than that, however, the PVC will
begin to degrade and release chlorides that are very bad for most museum
materials.  

Exhibit and Storage Materials Handbook by Paul Storch (you can google this
for a pdf) mentions this product, tested it for object safety and failed it
for all exhibit purposes.

http://www.cci-icc.gc.ca/publications/cidb/view-document_e.aspx?template=pri
nt&Document_ID=82
This document discusses many general types of museum products.  Scroll down
to the middle for plastics.

There is a 28-day non-quantitative test that many conservators use to
determine potential risks to objects.  Commonly called the ³Oddy Test,² it
is essentially an accelerated aging test in which three metals (chosen for
their presence in museum objects and their easily visible corrosion
products) are contained with a sample of a proposed material while heated at
low temperatures for a month.  Although the test is not really scientific,
it works fairly accurately as a predictor.
http://www.metmuseum.org/Works_of_Art/objects_conservation/spring_2003/oddy.
asp

Sintra is not recommended for any long-term application in a museum.
However, Dibond, also produced by Alcan Composites, has a very good
track-record and would be a safe alternative.
http://www.bayplastics.co.uk/Product%20Materials/prod-dibond.htm

Good luck with your new exhibit!
Victoria

Victoria Book
Conservator
Sam Noble Oklahoma Museum of Natural History
University of Oklahoma
2401 Chautauqua Avenue
Norman, Oklahoma   73072-7029
phone 405.325.5163
fax 405.325.7699
www.snomnh.ou.edu

On 3/9/06 9:56 AM, "kwellspring" <kwellspring at amherst.edu> wrote:

> Greetings List,
> 
> We are considering using a PVC material (produced by Alcan Composites,
> marketed under the name Sintra) to line shelves in  closed display cases for
> some new exhibits. The MSDS for Sintra lists its components as polyvinyl
> chloride, lead compounds, calcium carbonate, titanium dioxide and 15-25%
> "other". It is advertised variously as "acid-free" "archivally sound" and as
> having "little out gassing".  The cases will contain primarily
> vert/invert/paleobotantical fossils, and some osteological material, and some
> specimens may be in direct contact with the Sintra liner.
> 
> Does anyone have experience in working with Sintra in exhibit cases? Can you
> suggest ways in which I could determine whether it is an appropriate inert
> material for exhibiting specimens for the next 20 years?
> 
> Many thanks,
> 
> Kate Wellspring
> 
> ______________________________
> Kate Wellspring
> Collections Manager
> Amherst College Museum of Natural History (formerly the Pratt Museum)
> Amherst College
> Amherst MA 01002
> (413) 542-2165
> www.amherst.edu/museumofnaturalhistory
> 





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