[NHCOLL-L:1735] container troubles

[emoore at vmnh.org]

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