Coil Form Sealing?

From:  Esondrmn [SMTP:Esondrmn-at-aol-dot-com]
Sent:  Friday, April 17, 1998 10:17 AM
To:  tesla-at-pupman-dot-com
Subject:  Re: Coil Form Sealing?

In a message dated 98-04-16 00:02:06 EDT, you write:

 I now have my 6" PVC coil-form.  I've sanded it inside and out and it's now
 drying under a heat lamp.  My question is what to use to seal it with
 (before and after winding).  I have oil based polyurethane and spar varnish.
 I'm leaning towards the polyurethane since a test shows it is thicker and
 adheres better to the 200 oC magnet wire.  Although the spar varnish has
 proven to be very durable on previous projects.  What are your suggestions?
 Almost forgot to say that I will keep the secondary turning on the winding
 jig while the sealer dries. 
 Brian B.  

I used a 6" dia pvc form prepared as you described.  I used oil based
polyurethane and applied about 5 coats on the bare form and them applied about
6 coats over the finished windings.  You are correct, keep the form turning to
prevent sags and runs.  Don't use a heat lamp to accelerate drying, it causes
air bubbles to form in the polyurethane.

Ed Sonderman