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RE: [TCML] Polyurethane Finish Questions

Hi Gary,

I like to think that the oil base poly I use does some electrical as well as
mechanical damage protection.

Granted its not Dolph's 43 but it would be interesting to compare. Saying
polyurethane is for coating floors strikes me a little like saying HDPE is
for cutting boards. - No flame intended!

I have particular interest at the moment as I have a mongo transformer that
I would like to encapsulate the secondary(HV) in clear 2 part or...??epoxy.
It is supposed to be rated at 14440 which is hard to believe given its
construction. It is meant to be run dry too.

Also it is fair to say the coating is an issue in very HF coils. I have a
polystyrene thin form for this purpose. Everyone's mileage and opinion will
vary ;-^)

Jim Mora

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Lau, Gary
Sent: Wednesday, April 22, 2009 6:02 AM
To: Tesla Coil Mailing List
Subject: RE: [TCML] Polyurethane Finish Questions

Hi Greg,

Just how much cleaning is needed?  If it's just surface dust from lying on a
shelf, I would imagine that pretty much anything will do - water, Windex,
rubbing alcohol, whatever, provided you give it sufficient time to dry
thoroughly after cleaning.  If you're in a hurry to use it, then avoid the
water-based products.

As far as metallic drying agents, I've not heard that, but I've not looked
into it.  Realize that polyurethane is made strictly for finishing floors
and such, and that insulative qualities are not likely taken into
consideration in their formulations.  Also, dielectric constant and
dissipation factors are don't-cares for covering a secondary.   This is why
acrylic is OK to wind a secondary on, but not OK as a tank cap dielectric.
But my gut tells me that as long as the product is clear, it's probably OK
to cover a coil with.

Regards, Gary Lau

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of G Hunter
> Sent: Tuesday, April 21, 2009 9:10 PM
> To: tesla@xxxxxxxxxx
> Subject: [TCML] Polyurethane Finish Questions
> What's the safest way to clean a secondary coil coated with oil based
> polyurethane?  I have paint thinner and also denatured alcohol on-hand.
Should I
> buy turpentine or mineral spirits?  I don't want to ruin the glossy
finish.  I just want
> to clean off dust, dirt, and fingerprints.
> I've also recently read that polyurethane oil finishes may contain
metallic drying
> agents, including zinc. Metals in the varnish? Seriously? Why doesn't this
ruin the
> dielectric qualities of the cured poly?
> Cheers,
> Greg

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