>Surely others have seen a similar case of foam liner "disease"
>(decay). Perhaps you would not notice the damage in a shell that is
>not naturally glossy. I wonder how safe (or not) the widely used
>blue foam inserts are for storing shells in the long run. The blue
>foam liner in this case is discolored near and under where the shell
>was stored. It also looks a little different from some of the new
>ones I see in use, so perhaps it is a different material.

 From my teens (1974) I kept my (what was then a small collection of)
shells in a wooden cabinet, using an orange foam plastic as liners.
The collection lived in this cabinet with these liners until I packed
it away in 1984 or so, when I moved town. The wood was a local and
very hard "softwood" called rimu (ree-moo, a podocarp, I think)

When eventually I looked into the cabinet again some of the liner
squares had deteriorated, but not in a crumbly fashion, and the
shells had not been affected by their proximity to it.

I replaced this with slightly thicker pale-blue furniture-foam of
unknown composition; this has since yellowed slightly, despite being
stored in the dark. Again, after about 20 years' use, no damage has
occurred to the shells and the foam is still fully-pliable.

I have had problems with Byne's and glass "diseases", but those are
unrelated and occurred in particleboard cabinets, or in glass tubes
(soda glass) stored at work.

>Charlie Sturm's nice paper on Archival and Curatorial Methods*
>(2006) mentions foam liners in specimen trays, and recommends
>polyethylene foam, which can be archival. He warns against
>polyurethane foam (foam rubber), which is not archival and will
>degrade over time, giving off acidic vapors. He also discusses the
>archival nature of plastics, but does not does not elaborate further
>on foam liners.
>
>Speaking of archival foam liners, can anyone recommend a supplier
>(off-list if you don't want to advertise on the list).

As part of my work, as informal curator of fossils, I looked into
archival foams. They are available, but certainly not cheap (now I'm
searching my study for the samples).  Ultralon is made in NZ, but is
available in the US (www.dunlopfoams.co.nz). It is closed-cell foam
available in a variety of densities & color and can have stabilizers
added on request. It is made of polyethylene (PE),
ethyl-vinyl-acetate copolymers (EVA) or a "high-tech" coblended
polymer (unspecified). Thong soles are made of this stuff.

Ethafoam is a coarsely-bubbled acrhival-quality foam used my museums,
but due to its coarseness may not be suitable for cabinet drawers.
--
Andrew Grebneff
Dunedin
New Zealand
Fossil preparator
<[log in to unmask]>
Seashell, Macintosh, VW/Toyota van nut

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