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<p>To some degree, this may depend on how often you foresee vials
needing to be opened.</p>
<p>Case in point: we have a massive collection of the immature
stages of insects, numbering nearly 10,000 vials. For decades, the
former curator had to keep topping off these vials because of
ethanol evaporation. In all those decades, apparently only one
person had ever made use of any of the specimens in that
collection besides the professor who had built that collection as
his personal research project. <br>
</p>
<p>So, what we did was to buy several thousand hospital-grade
Vacutainer serum glass test tubes with red rubber "injection port"
stoppers, designed to be used by hypodermic puncture of the
stopper. It turns out that the little 1-dram shell vials that we
already had in stock by the tens of thousands (and a few larger
sizes of shell vials) are <b>the exact same diameter</b> as these
standard blood sample test tubes, and those stoppers fit
perfectly. We removed the stoppers from the test tubes,
transferred all of the contents of the old vials into shell vials,
and put the stoppers in by inserting a hypodermic needle in the
cap to release the pressure and then sealing the vials. While this
did leave us with thousands and thousands of useless test tubes,
it was - for whatever odd reason - <b>significantly</b> cheaper
to buy test tubes with stoppers in them than it was to just buy
the exact same stoppers in bulk. At the time, I think it was only
about 15 dollars per 100 test tubes, and about 50 cents per
stopper. Looking online now, those stoppers appear to sell for 85
cents each, and the Vacutainer tubes with those exact stoppers are
35 dollars per 100. Go figure.<br>
</p>
<p>That was 15 years ago now, and the stoppers are in perfect shape,
and we haven't lost a milliliter of ethanol, cumulative - except
for the two or three vials that have been opened in those 15
years. I would rate this as an incredible success, with the one
qualification being that you can't put the stoppers back without
using a hypodermic needle to release the pressure. That's why, for
a very actively-used collection, this approach might create some
real headaches.</p>
<p>The old neoprene stoppers (we had black ones, green ones, and
gray ones) all seemed to swell up or even dissolve from prolonged
contact with ethanol, but these red ones show no signs of any
problems to date, and maybe they are actually archival. It may
take another 25 years or so to be certain. Regardless, we have no
more vials with neoprene stoppers or plastic stoppers. More
heavily-used parts of our collections that are kept at room
temperature utilize either the "many vials inside a bigger vial"
system that many people practice, or use screw-cap vials with
cone-shaped plastic cap inserts that drastically reduce
evaporation. We use different storage systems for ethanol samples
kept in the freezer, and evaporation isn't an issue.<br>
</p>
<p>I don't have all of the specs and supplier and manufacturer data
handy, but anyone seriously interested should not have too much
difficulty figuring out how to do the same thing we did.</p>
<p>Peace,<br>
</p>
<pre class="moz-signature" cols="72">--
Doug Yanega Dept. of Entomology Entomology Research Museum
Univ. of California, Riverside, CA 92521-0314 skype: dyanega
phone: (951) 827-4315 (disclaimer: opinions are mine, not UCR's)
<a class="moz-txt-link-freetext" href="https://faculty.ucr.edu/~heraty/yanega.html">https://faculty.ucr.edu/~heraty/yanega.html</a>
"There are some enterprises in which a careful disorderliness
is the true method" - Herman Melville, Moby Dick, Chap. 82</pre>
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