Re: Secondary construction

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

Original poster: "Dr. Duncan Cadd by way of Terry Fritz <twftesla-at-uswest-dot-net>" <dunckx-at-freeuk-dot-com>

Date: 12 January 2001 15:26
Subject: Secondary construction


Hi Paul!

>Original poster: "Paul Benham by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <Paulb-at-woodanddouglas.co.uk>
>
>I am soon going to build my first secondary.  I will sand
the tube to
>remove the writing on it, but should I then varnish it
before I wind it?
>
>Thanks,
>
>Paul.


If it's a cardboard tube, yes, definitely.  If it's a
plastic tube, probably and cautiously - acrylic doesn't take
kindly to many types of varnish. PVC, PP, PE are no problem
with varnishes.  Apparently, varnishing PVC makes a
difference, but I've never used PVC yet, so can't comment.
I'd think that any plastic would be fine without, but a coat
of varnish certainly won't hurt anything, I suppose it
depends on how impatient you are to start winding that coil
;-)

So far, I've used only cardboard and bakelite tubes.
Cardboard I have varnished with polyurethane (e.g. Ronseal
woodglaze) and with shellac and both are good.  I have also
used cardboard tubes and soaked them in beeswax and that's
fine too.  Bakelite I have used polyurethane with and that
was OK.

Steer clear of emery paper for the sanding job.  I've read
that crude emery contains semiconducting muck which may ruin
your chances if any specks of it get left behind on the
tube.  Ordinary sandpaper and wet&dry are fine though.

Dunckx