Re: Mutant Tar!!

To: tesla-at-pupman-dot-com
Subject: Re: Mutant Tar!!
From: FutureT-at-aol-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Tue, 25 Apr 2000 18:29:34 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

In a message dated 4/25/00 12:32:53 AM Pacific Daylight Time, 
tesla-at-pupman-dot-com writes:

> Original Poster: "Brad DiGiovine" <Guido28-at-mediaone-dot-net> 
>  
>  to all,
>  
>  i have had a NST sitting in gasoline for the past month unpotting and it
>  is still not all off.  I can barely see the windings.  Has anyone else
>  ever run into this?  my 12kv30ma NST only took a week, and this 15kv30ma
>  is taking a lot longer.  Are there better solvents for unpotting than
>  gasoline? thanks
>  
>  Brad DiGiovine
>  

Brad,

Generally folks remove the bulk of the tar first by using hand tools.
One way to do this is to put the NST in the freezer overnight to make
the tar brittle, then chip it off with a hammer and screwdriver.  Another
way is to heat the NST in an oven to soften the tar so it can be 
sloughed off easily.  Another way is to hold a heat gun to the NST
to soften the tar as you go along scraping the tar off.  After most of
the tar is removed, then it is soaked in the gasolene or kerosene.
Don't combine heat and gasolene or kerosene techniques for obvious
safety reasons.  Be careful not to damage the coils when scraping off
the tar.

Another thing to keep in mind is that all tar is not the same.  Jefferson
brand NST's use a silica filler in the tar which makes it much harder to
deal with. 

Some folks find the process too frustrating and wind up tossing the
NST off a high cliff.

Cheers,
John Freau