Storage containers for Specimens Preserved in EtOH or FAA
Diana G. Horton
dhorton at VAXA.WEEG.UIOWA.EDU
Mon Dec 5 14:02:55 CST 1994
Storage containers for specimens (eg. aquatic plants like
Lemnaceae) in EtOH or FAA: some answers and another question!
Since I have spent (too much) time trying to find out how best to
store specimens of such small aquatics as Lemnaceae, I thought I
might as well share what I have found out.
1. Storage containers.
The traditional storage container, glass jars, appear to be the
best. I was warned against plastic by Rob Colwell (University of
Connecticut) who wrote that they lost collections of a mite
stored in plastic containers *purported to be suitable for EtOH*
due to slow 'crazing' of the plastic over period of several
The type of lids is an important consideration. According to
Suzumoto (in C. L. Rose & A. R. De Torres. 1992. Storage of
Natural History Collections: Ideas & Practical Solutions.
Published by SPNHC - Society for Preservation of Natural History
Collections), the best combination is a *polyethylene liner with
polypropylene lids*. Collections currently in the University of
Iowa Herbarium, which I imagine is representative of many
herbaria, have either Bakelite lids or metal lids. There are
problems with both of these according to Suzumoto.
2a. Bakelite and metal lids should not be used.
Bakelite lids (smooth black lids that look like plastic) are not
good for the following reasons:
"Bakelite fails to provide a reliable closure for formaldehyde
and alcoholic solutions because the vapours embrittle the resin.
Also Bakelite has a different expansion/contraction rate than
glass, so any temperature variations over time will lead to
loosening fo the lid."
Metal lids are not good for the following reasons:
"...all eventually corrode. Rusting from the inside out is
especially severe for jars containing formaldehyde solutions.
.... Metal lids do not loosen as readily as Bakelite lids, but
the cardboard liners are subject to compressive set and
shrinkage, leaving gaps which allow evaporation. The performance
of metal lids may be improved by replacing the pulp liners with
die-cut polyethylene liners. However, metal lids should be
replaced by polypropylene lids."
*Where* can one obtain glass jars with polypropylene lids and
polyethylene liners?? Ward's has either metal or bakelite lids.
Fisher doesn't seem to have anything suitable, nor does Carolina.
Neither Herbarium Supplies nor University Products carry jars.
Where does one get them?!
-- Diana Horton
University of Iowa Herbarium
Iowa City, IA 52242
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