Coil Form Sealing?

From:  D.C. Cox [SMTP:DR.RESONANCE-at-next-wave-dot-net]
Sent:  Saturday, April 18, 1998 11:26 PM
To:  Tesla List
Subject:  Re: Coil Form Sealing?

to: Brian

Avoid the polyurethane -- will crack with time and becomes unsightly.  A
good sealer to use is 3 light coats of G.E. Glyptal which is available in
quarts through almost all large electric motor repair shops.  Be sure to
apply to inside using a rag taped to a wooden dowel.  Use xylol as the
thinning agent and strain the glyptal through standard paint filters after
stirring for 5-6 minutes with an electric drill stirrer.  Glyptal may also
be used as the finishing sealer as well although if using enameled magnet
wire a better choice is Dolph's AC-43 air dry varnish.  Has a.n excellent
dielectric and insulating properties.  Bullseye clear shellac is also a
better choice than polyurethane as it doesn't crack either.


> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-pupman-dot-com>
> Subject: Coil Form Sealing?
> Date: Saturday, April 18, 1998 6:04 AM
> ----------
> 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
>  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
>  I'm leaning towards the polyurethane since a test shows it is thicker
>  adheres better to the 200 oC magnet wire.  Although the spar varnish has
>  proven to be very durable on previous projects.  What are your
>  Almost forgot to say that I will keep the secondary turning on the
>  jig while the sealer dries. 
>  Thanks,
>  Brian B.  
>   >>
> Brian,
> 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
> 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
> air bubbles to form in the polyurethane.
> Ed Sonderman