[NHCOLL-L:1739] Re: container troubles

[Simmons, John E]

Elizabeth, 
Concerning the polystyrene:
I think it is possible that you have a bad batch of polystyrene.  However,
keep in mind that pesticides in the museum are not the only thing that might
affect it.  Polystyrene is affected by compounds containing benzene rings,
which napththalene does, which is why the caution about polystyrene around
moth crystals.  However, you could have another source of benzene ring
containing compounds in the museum such as a floor stripper or sealant.  The
standard caution for using polystyrene in museum collections is to avoid
exposure to "solvents, solvent vapors, or fumigants."  

Also, these lids might have been exposed to benzene rings while in
production, storage, or shipment before they got to your museum.

Concerning polyethylene
If I understand your message correctly, you are saying that the lids that
are cracking are composed of low density polyethylene.  Polyethylene is
susceptible to UV exposure.  If these lids are sitting under unfiltered
fluorescent lights, or have been out in the sunlight, that could be the
cause of the cracking.  Low density polyethylene can also be affected by
some chemical agents.  Generally speaking, polyethylene is a safe material
to use in museum collections, but you do have to be cautious about its
exposure to light (in particular), to some chemicals, and to high heat
(particularly if it is low density polyethylene).  The low density is used
in the lids because it is more flexible than the high density, but it is
also less stable.  I have seen lots of polyethylene containers go bad after
exposure to light.  You may see this as discoloration, cracking, or crazing,
sometimes all three.

--John

John E. Simmons
Collection Manager, Natural History Museum
and
Coordinator, Museum Studies Program
University of Kansas
Dyche Hall
1345 Jayhawk Boulevard
Lawrence, Kansas 66045-7561
Telephone 785-864-4508
FAX 785-864-5335
jsimmons at ku.edu
www.ku.edu/~museumst/


-----Original Message-----
From: emoore at vmnh.org [mailto:emoore at vmnh.org] 
Sent: Wednesday, October 23, 2002 12:18 PM
To: Cindy Ramotnik; nhcoll-l at lists.yale.edu
Subject: [NHCOLL-L:1738] Re: container troubles

Dear Listers,

After some more investigating, here's what I have found out:

The caps are low density polyethylene.
The manufacturer doesn't know why they would be cracking.  
They were purchased at different times.
I am 100% sure that we have never used pesticides (not even napthalene)in
that collection.  Our mammalogist has been here for the history of the
collection and would know and is aware of the hazards of using pesticides on
those containers.

Thanks.

Elizabeth


---------- Original Message ----------------------------------
From: Cindy Ramotnik <ramotnik at unm.edu>
Date: Wed, 23 Oct 2002 11:27:06 -0600

>  Elizabeth, I have a few thoughts on your question. Have you contacted 
>the manufacturer to find out if they have any ideas what might have 
>caused the lids to crack? Were the containers purchased all at the same 
>time/year or are different times? If the former perhaps you received a 
>"bad batch." The manufacturer might know about this. Also I am curious 
>as to why the lids crack but not the container-- we use plastic skull 
>vials in our collection and have noticed that many have "crazed" 
>(cracked) over time due to past exposure to chemicals like PDB or 
>napthalene. Are you 100% there's no history of pesticide use in the 
>collection?
>
>Good luck,
>Cindy
>
>Cindy Ramotnik
>U.S. Geological Survey
>Museum of Southwestern Biology
>University of New Mexico
>Albuquerque, NM 87131
>
>emoore at vmnh.org wrote:
>
>>Dear fellow listers, 
>>
>>We are having some trouble with platic containers and are hoping that 
>>someone out there might have some information or experience with this
thatthey can share. 
>>
>>Our mammalogist currently uses Fisher brand clear polystyrene containers
with white opaque lids to hold skeletal materials.  I think the lids are
polystyrene as well; it doesn't specify otherwise in the catalog.  These
containers and the lids are stored in plastic bins to keep them clean until
used. I don't know what kind of plastic the bins are made of, they are the
inexpensive plastic storage bins with snap-on lids that you can pick up at
any discount store. 
>>
>>Our problem is that the lids to the specimen containers have become 
>>brittle and snap and break when you open the containers.  Even lids that
are only a couple of years old are breaking with one time use.  The
containers are not breaking. 
>>
>>Is this a problem with polystyrene containers/caps
>> in general?  Could this have been accelerated by storing them in closed
plastic bins?  Has anyone else had this happen?  If so, did you figure out
why? 
>>
>>We do not use pesticides/insecticides in the collections storage units so
there should be no interaction with added chemicals to trigger a reaction.
There are also no chemicals used in the specimen prep process.  Tags in the
containers are archival/acid free.  The containers and lids are stored in a
dark closet until used then as they are filled they are stored in closed
specimen cabinets so there is very little exposure to UV.  The storage
closet is in a temp controlled lab area so there should be only normal temp
fluctuation to affect the containers/lids. 
>>
>>Can anyone think of any other factors that might affect the longevity of
these lids?  Has anyone else been using them and, if so, what is your life
expectancy with them? 
>> 
>>Thanks for any help you can offer. 
>> 
>>Elizabeth Moore 
>>
>>__________
>>_______________________________________________________ 
>>Dr. Elizabeth Moore 
>>Curator of Collections and Archaeology, Assistant Director for Science and
Learning 
>>Virginia Museum of Natural History 
>>1001 Douglas Avenue 
>>Martinsville, VA 24112 
>>emoore at vmnh.org 
>>www.vmnh.org 
>>
>
>
>
>