Metal traces in PVC pipe?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Garry Freemyer" <garryfre@xxxxxxxxxxx>

I've had three or more Tesla coil secondaries die from flaring out the side
of the secondary coil. I've just finished an autopsy on the secondaries and
discovered a bit of a surprise.

The coils flared in several areas when I removed the wire, I noticed narrow
or large holes burned into the PVC as if there were arching to something
within the pipe! When I dug into the holes I discovered pieces of steel
colored metal, one quite large underneath but mostly were just tiny bits of
metal embedded into the plastic. These could not be from the wire as it is
copper with red enamel, and copper is yellow not chrome/steel colored.

Now I know the cause of such catastrophic failures, but I am perplexed as to
the source of these metallic traces. Do the makers of this pipe use metal in
the shaping and polishing of such pipe? I would think they would use molds
rather than other means, but who knows. Is there a part of the manufacturing
process that involves metal that might create metal pieces that might fall
into the plastic?

Is there anyone on the list familiar with the manufacture or other means
that might explain the presence of such metal fragments within the plastic?

Are there other possible conductive impurities that might account for this,
that might result in a reaction producing metal to appear on failure?

I have noticed that I have experienced no such failures on any coil that
isn't wound around pvc pipe.