From: "Seymour, Janet I - WHS" <Janet.Seymour@wisconsinhistory.org> Date: Mon, 20 Jul 2009 12:13:49 -0500 Subject: Diplay cases - appropriate materials Message-ID: <488E289A5C909049B0E55F6B651B5B3501421A140644@MEWMAD0PC01G02.accounts.wistate.us>
List Serve Members -
For those of you considering making or purchasing display cases, here is so
me important information about what types of materials are appropriate and
won't damage artifacts.
If you have display cases made of materials that can cause damage, there ar
e also suggestions for improving the conditions.
Please contact me directly if you'd like more information on the topic.
Janet
Display Cases
Materials such as wood, plywood, paint, foam and fabric can emit harmful va
pors into a case environment, subjecting the objects to damage. Acid migrat
ion from wood is especially harmful to textiles and paper, causing yellowin
g and embrittlement. Corrosive volatiles, released by certain glues, paints
, fabrics and urea formaldehyde in plywood, cause metals to corrode.
If your exhibit cases are made of wood, painted or unpainted, place Mylar u
nder items on display. Mylar creates a barrier from the acids in the wood.
Make sure there is filtered air flow through these cases, too, in order to
avoid a build up of acidic fumes.
When constructing new exhibits, consider constructing cases out of inert ma
terials, such as Plexiglas and metal.
Materials for display cases
The materials listed below can be considered as inert in terms of their che
mical interaction with museum objects. They are safe for use in constructin
g tightly sealed environments providing good protection against externally
generated pollutants and variations in external humidity.
* Glass and other vitreous systems
* Rigid plastic materials such as acrylics (Perspex™, Plexiglas™) an
d polycarbonates (Makrolon™). Unplasticized polyvinyl chloride (uPVC) str
uctures are also likely to be stable for the periods in question although t
here is a small risk of the emission of HCl over longer time periods
* Unbleached, undyed cotton
* Acid free paper and card (“archival quality”)
* Metals – but beware of the possible problems due to electrode potent
ials between different metals
* Powder coated metals (if appropriately baked)
* Alcoxy (non-corrosive, alcohol curing) silicones
* Silica gel
* Polyester films (Mylar™ D, Melinex™, etc.)
* Polyethylene, polypropylene, and other “virgin grade” polymer film
s not containing plasticizers etc
* Carboxy methylcellulose adhesive.
Janet Seymour
Field Services Representative - Northern Region
Wisconsin Historical Society
Voice: 715-836-2250
Collecting, Preserving, and Sharing Stories Since 1846
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