We use thick black rubber septa made by Geo-Microbial Technologies. I 
haven't tested them with a vacuum gauge, but they are the most 
gas-tight septa I've come across.

On Mar 16, 2006, at 6:02 PM, Greg Michalski wrote:

> Any consensus on the best material/brand for making a vacuum tight 
> crimp
> seal? Im using a teflon/PFTE but they are not sealing below 10-2 
> unless I
> use a little hi vac grease...
>
>
"...I do not believe totality can be contained in language; my problem 
is what remains outside, the unwritten, the unwritable. " - Italo 
Calvino, If On a Winter's Night a Traveller

Yit Arn Teh, Ph.D.
Postdoctoral Scholar
Rhew Laboratory
Department of Geography
507 McCone Hall
University of California
Berkeley, CA 94720-4740

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