Date:         Sat, 18 Aug 2007 23:36:20 -0400
Reply-To:     Conchologists List <CONCH-L@LISTSERV.UGA.EDU>
Sender:       Conchologists List <CONCH-L@LISTSERV.UGA.EDU>
From:         csturmjr+@PITT.EDU
Subject:      Re: Foam liner "disease"
In-Reply-To:  <3aa9658f0708101754y57bbf00cxb5cb6c6e160cb324@mail.gmail.com>
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Fabio and others,

I have just finished unpacking a collection that Tim Pearce and I picked
up in Florida. The collection was meticulously cataloged. About 80% of the
collection was fossil material, 20% recent. Some of the specimens were
stored in open trays with foam in them, some in plastic boxes with foam.
Most of the foam was black, some was green. I started referring to it as
the "black foam from hell."

I wish that I had kept some notes while unpacking the collection, however,
I did not. The collection was built over 30-40 years. Some of the
specimens may have been exposed to the foam for a long time. Sometimes the
foam was stable and spongy, most of the time it was crumbly and
disintegrated in your hand, other times it was a doughy consistency.
Shells that were exposed to "the black foam from hell" sometimes showed no
changes (at least to the naked eye), most of the time they did show
changes. The changes ranged from some discoloration of the shell all the
way to the surface of the shell being a powdery mess. The reaction seemed
to be due to contact as the shell surface that was not in contact with the
foam seemed to be unaffected. The foam seemed to be a polyurethane foam
(foam rubber) and this product should be banned from any collection.

Polyethylene foam tends to be harder, not as compressible as polyurethane
foam. For this reason, it may not meet the needs of some collectors. One
can use polyethylene fiber but it may catch on some frilly or spinous
shells.

An interesting aspect of polyethylene foam is what agent is used to foam
or puff-up the material. If nitrogen is used, then the gas in the foam is
neutral and will cause no problems down the road. It is possible that the
foaming agent may not be archival. For this reason, I like procuring
material from suppliers who can provide such information or purchase from
a firm dealing with archival materials. Some of them are listed at the end
of my chapter (glad you liked it).

Regards,
Charlie
.................................................
Research Associate - Section of Mollusks
Carnegie Museum of Natural History
Pittsburgh, PA, USA

Assistant Professor - Family Medicine
Fellow-American Academy of Family Practice
Fellow-Academy of Wilderness Medicine

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