Re: New 4" coil: R.Hull and CSN, Secondary Varnish

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

> Dave,
> 
> If you need multiple coats of varnish to build up a thick layer of
> insulating material to suppress corona or racing arcs, your coil is
> either not designed properly, tuned properly, or both. I use a couple
> coats of old fashioned shellac for no reason other than to hold the
> wire in place.
> 
> A thick coating would be desirable on a coil that is torn down and
> transported frequently to protect the windings from physical damage.
> 
> Ed Wingate RATCB

	I don't have Ed W's experience here, but I have always had good luck
with plain old orange (like the color better) shellac.  I've used
polyurethane, but don't think it worth the trouble.  I've only built
coils up to 5-1/4" OD, but they worked fine with shellac-impregnated
paper mailing tubes, head dried and really soaked with multiple coats. 
I usually peel off several inner layers of the tube after the first
outside coat, as this lightens the form and doesn't use as much
shellac.  I'm sure some other forms are "more professional", but the
paper with shellac on it is easy to wind on, as the turns don't really
want to slip.

Ed