[NHCOLL-L:5627] Re: Gaskets for wet collection vats

[John E Simmons]

Gaskets are the bane of tank-stored specimens.  It is the nature of
compressible materials to lose their compressibility with time, which means
the gaskets fail; exposure to alcohol will degrade most compressible
materials even faster.

I think Andy Bentley's advice about checking with Delta Designs is sound--I
have had several discussion with the Delta folks over the years about tank
gaskets, and I know they are always on the lookout for something better.

EPDM, buna-n, and the other synthetic rubber-like products used for gaskets
for jars with glass closures are possibilities, but usually the tolerance on
a large tank is so wide that these materials are not compressible enough to
do the job--worth checking into, though.  Also the cost per gasket would be
high (it would require a lot of material and a special die to cut it).  A
radical alternative is to design a "fluid gasket" in the form of a tray of
mineral oil into which the lip of the lid would sit.  It would be a pain to
open and close without getting the oil in the tank, but it might be worth
pursuing.  The oil should act as a barrier against evaporation of the
alcohol, but I don't know how it would perform against oxygen permeance.

In 1992, Arnold Suzumoto of the Bishop Museum published an interesting paper
suggesting the use of closed-cell foam weatherstripping or extruded
polyethylene rope for sealing large containers. The reference is:

Suzumoto, A. Y.  1992.  New materials for sealing old crocks.  *Collection
Forum* 8(2):68-72.

It would be worth checking with Arnold to see how these products held up for
him, and if he has any further recommendations.

If you find a good replacement gasket, please let all of us on NHCOLL-L know
about it--this is a perennial problem for everyone that keeps specimens in
large containers.

--John

John E. Simmons
Museologica
128 E. Burnside Street
Bellefonte, Pennsylvania 16823-2010
simmons.johne at gmail.com
303-681-5708
www.museologica.com
and
Adjunct Curator of Collections
Earth and Mineral Science Museum & Art Gallery
Penn State University
University Park, Pennsylvania
and
Lecturer in Art
Juniata College
Huntingdon, Pennsylvania


On Fri, Sep 2, 2011 at 2:01 PM, Frederick, Moretta RBCM:EX <
MFrederick at royalbcmuseum.bc.ca> wrote:

> I need to find a replacement for the gaskets lining the lids of our fluid
> storage vats, and am interested in hearing what materials others are using
> to seal their large storage containers, as well as suggestions for suppliers
> in North America.****
>
> ** **
>
> We are looking to seal two types of vats, both of which are used to store
> fish or invertebrate specimens in ethanol or isopropanol.  The vats are not
> opened often (~2-10 times a year), and the material used will need to
> prevent evaporation as well as hold up well against alcohol fumes and fish
> oil.  Ideally, we would like to find something with a peel and stick side so
> it can be attached directly to the lid.****
>
> ** **
>
> Our larger vats (4’x6’) are fiberglass with flat mating lips, held closed
> with through bolts every 12" or so. ****
>
> ** **
>
> Our smaller vats are HDPE, about 3'x4' with a gravity sealed lid that slips
> over the vat and has a groove in it to hold the gasket. We are hoping to
> create a tighter seal on these vats with strapping. The groove is about 1/2"
> in diameter and previous gaskets were simply stuffed into this space with no
> adhesive.  We have found however that over time these gaskets slip out,
> falling into the vat, so we are hoping to find something that we can adhere
> inside the groove.****
>
> ** **
>
> Thanks for any advice you can give me!****
>
> ** **
>
> Cheers, ****
>
> ** **
>
> Moretta****
>
> *
> ______________________________________________________________________________________________
> *****
>
> *Moretta Frederick *     Collections Manager, Invertebrates, Fish,
> Amphibians, Reptiles  |  Natural History
> [image: Description: https://sales.royalbcmuseum.bc.ca/logo.jpg]
> 675 Belleville Street, Victoria, BC Canada V8W 9W2
> T 250 387-2932
> MFrederick at royalbcmuseum.bc.ca   |   www.royalbcmuseum.bc.ca   |
> www.bcarchives.bc.ca ****
>
> Prepare to be puzzled. Curators, archivists, and conservators are
> practicing their poker faces for October 6
> when they fib in the name of fundraising at *Artifact or Artifiction<http://www.royalbcmuseum.bc.ca/Plan_Visit/aora.aspx>
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>
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>



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