OK, I know what you guys are talking about now with the Teflon tape.
It's the same thing I wrap around my copper tubing fittings when I hook
up my propane tanks to the house. Got it. I'll try it. 

The glass lid with pressure seal is out of my budget I'm sure.
Interesting to know that's what they use at the smithsonian Britt. 

I'm starting a fish collection here for the organization I work for,
that sprouted out of my wanting to illustrate for the state from
specimens rather than photos. I'm up to 40 species to date. Its been
really fun to work with biologists to correctly ID the fish. I'm totally
into sculpin at the moment.

Catie  
-----Original Message-----
From: SciArt-L Discussion List-for Natural Science Illustration-
[mailto:[log in to unmask]] On Behalf Of Gail Guth
Sent: Wednesday, February 04, 2009 8:14 AM
To: [log in to unmask]
Subject: Re: [SCIART] Tape for sealing specimen jars

teflon tape fills gaps very nicely, and molds itself into whatever  
space is available. The rear-view mirror on my '84 car was loose,  
rattling, and un-repairable, so I wrapped a bunch of teflon tape  
around the base where it connects to the car. It took quite a bit of  
tape, but it worked very well, no wobble.

Gail




On 12 /09/08    , at 02 /04/09,  11:44 AM, Britt Griswold wrote:

> The Smithsonian uses glass lids held in place with the traditional  
> fruit canning mechanism: a rubber gasket and a pressure seal  
> applied with the metal lever lock. Though the teflon covered  
> threads sounds promising...
>
> Britt
>
> Bruce Bartrug wrote:
>> Catherine Bursh wrote:
>> On the tape subject.... Anyone know the correct tape to use to  
>> seal the
>> lids of specimen jars with alcohol in them? I'm tempted to use black
>> electrical tape but not sure if the alcohol fumes will mess with the
>> glue on the tape.
>> The purpose of the tape is to slow the evaporation that takes  
>> place even
>> with a threaded top.
>> Catherine, I have two suggestions for you -- neither of which,  
>> however, I've actually tested for the purpose you indicated.
>> The first is teflon plumbers' tape.  Which is not really tape per  
>> se (it has no adhesive) but is simply a thin film of a very inert  
>> and useful material.  One wraps the tape on the threads to be  
>> sealed and tightens the lid.  Very good at sealing the slightest  
>> leaks, even in gas lines.  I used it many decades ago to seal  
>> brass joints in gas lines for chromatographs -- a instrument used  
>> to analyse chemical substances.  Try to find some wide enough to  
>> fit the threads in question.
>> The second is a type of seal used to seal lids of packaged  
>> chemicals.  It's a circular sleeve of shrink-wrap type material  
>> that one positions around a jar or bottle lid and then shrinks  
>> with a hair-dryer.
>> As I said, I've not tested these specifically for the application  
>> you've mentioned, but I strongly suspect using both would  
>> significantly reduce alcohol evaporation from a speciman  
>> container.  I'm suspecting you're already using glass jars and  
>> metal lids?
>> /Suerte/,
>> Bruce

Gail W. Guth
Guth Illustration & Design
139 Lathrop Avenue
Battle Creek, MI  49014-5076
269-963-1311
FAX: 269-969-0652
www.guthillustration.com