[Nhcoll-l] [External] earthen plaster or clay plaster

[Callomon,Paul]

Bear in mind that plaster in older storage buildings can contain asbestos. This is true of most pre-war structures in the USA that were termed "fireproof" in their original specifications. The plaster is usually a mixture of gypsum and up to 60% asbestos fiber. Depending on your local regulations, you might not even be allowed to hang a hook in the wall now.
Gypsum plaster is hygroscopic. If water leaks into it, there is often a characteristic "bloom" with blistering of the paint and disintegration of the plaster. This is not especially hazardous (unless see above), but it makes a mess.

Paul Callomon MSc
Collection Manager, Malacology and General Invertebrates
________________________________
Academy of Natural Sciences of Drexel University, Philadelphia
1900 Benjamin Franklin Parkway, Philadelphia PA 19103-1195, USA
prc44 at drexel.edu<mailto:prc44 at drexel.edu> Tel 215-405-5096 - Fax 215-299-1170



From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> On Behalf Of Tacker, Christopher
Sent: Thursday, October 22, 2020 12:11 PM
To: Lennart Lennuk <Lennart.Lennuk at loodusmuuseum.ee>; nhcoll-l at mailman.yale.edu
Subject: Re: [Nhcoll-l] [External] earthen plaster or clay plaster


External.
Hi,  Lennart,
How hygroscopic are the plasters, and how do they fare when they get wet?
You might want to get your geology/ mineralogy curator to do some XRD to identify the components.
Regards,
Chris Tacker
R. Chris Tacker, Ph.D., P.G.
Curator of Geology
N.C. Museum of Natural Sciences
11 West Jones Street
Raleigh, NC 27601

________________________________
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Sent: Thursday, October 22, 2020 7:47:48 AM
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Subject: [External] [Nhcoll-l] earthen plaster or clay plaster

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Dear all



Do you have any experience about what materials use for collections rooms walls.

Is earthen plaster or clay plaster safe for collections?



Best regards!

Lennart Lennuk

Head of zoology

Estonian Museum of Natural History

+372 6603404, 56569916






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