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
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