We soak the Nafion in methanol. Interesting to hear that acetone can 
make it too soft... not a problem with methanol. By the way, don't 
use ethanol - mass of 46!!! That will leave you with a headache.

Select Nafion tubing TT-020, which when swollen with ethanol (let 
soak for a minute) will slip over 0.5mm OD capillary tubing then dry 
to a tight fit.

Paul Eby
University of Victoria




At 01:02 AM 21/11/2005, you wrote:
>Hi Karyne,
>Spit only works if it is at the correct pH and consistency.  You 
>need to make sure that your diet contains plenty of glutinous 
>material for a week prior to sealing the nafion.  I have found that 
>a diet of porridge, pine cones and treacle toffee works best.  Be 
>careful that you don't overdo the treacle toffee however,otherwise 
>the spit will solidify on contact with air and will not remain 
>liquid long enough to transfer to the nafion/fused silica joint to 
>ensure a leak-tight seal.
>Hope this helps,
>Steve
>
>P.S.
>Seriously, I have no idea where the spit thing came from. Normally 
>just dip the very end of the fused silica into some acetone and 
>carefully insert into the nafion tube by 1-2cm and leave to 
>evaporate. (The nafion tube will become too soft and collapse if too 
>much acetone is used).  If the nafion tube is too wide, try using 
>two short lengths of the next size fused silica and when sealed 
>couple up to these with the 320um.
>Or: using 320um throughout with 030 nafion, insert the 320 by 2cm 
>into the nafion and use a very small amount of something like 
>Araldite to seal the joint. If using this method carefully move the 
>fused silica backwards and forwards by a few mm just to ensure the 
>Araldite fills the joint, then leave to dry.
>Alternatively, use 020 nafion with 320um fused silica. This is a 
>tight fit but works well if you are careful.
>Steve
>
>
>>From: Karyne Rogers <[log in to unmask]>
>>Reply-To: Stable Isotope Geochemistry <[log in to unmask]>
>>To: [log in to unmask]
>>Subject: [ISOGEOCHEM] nafion tubing...what's your trick?
>>Date: Mon, 21 Nov 2005 14:25:28 +1300
>>
>>Hi Tim
>>
>>When Steve Welsh from Sercon was out to install the GC, he showed me how
>>to install the nafion, I've never had to do it since. I remember he said
>>just spit on your fingers etc, and the spit will act as glue and shrink
>>the nafion onto the fused silica. Well, I've tried spit, methanol,
>>ethanol, but nothing works, the tubing still slides off the fused silica
>>very easily. I'm using the nafion that came with the machine (TT-030). The
>>one that was originally on there looked like it might have had a bit of
>>glue over the join.... I can't remember if this is actually what happened.
>>The manual gives no clarification either...
>>
>>
>>Can you help???
>>
>>thanks
>>
>>Karyne
>>================================================================
>>Karyne Rogers                                   tel +64 4 570 4636
>>GNS Science                                     fax +64 4 570 4657
>>PO Box 31-312
>>Lower Hutt                                      email [log in to unmask]
>>New Zealand                                     www.gns.cri.nz/stable
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