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Re: Envirotex Lite coating tips
Original poster: "Scott Hanson" <huil888@xxxxxxxxxxxx>
Matt -
I'm not sure where you see any "disagreements on key issues" between
Terry's and my epoxy application processes .....certainly not
anything that should induce anyone to stick with solvent-based
coatings instead of at least trying epoxy.
Here are the differences that I see between Terry's procedure and
mine, and the reasons behind my suggestions.
1. Application brushes:
Terry suggests a 1" wide bristle brush, I suggest a 3-4" wide
disposable "foam brush".
I used the cheap disposable bristle brushes in the beginning, but
found that they continuously shed bristles into the coating. The foam
brushes shed nothing, and using a 3-4" wide brush just makes leveling
the coating go faster since you are leveling a wider section of the
coil. Obviously, using a wider application tool requires you to pay
more attention to keeping the edge of the brush perfectly parallel to
the axis of the coil. Also, the single, flat edge of the foam brush
seems to introduce less bubbles than the bristle brush. Remember that
in the final stages of smoothing, only the very tip of the brush is
contacting the coil, with only a few grams of pressure.
2. Use of Co2 to magically pop bubbles in the coating:
I think this is actually stated in the Enviro-Tex literature.
However, there is no mechanism (physical or chemical) that I can
think of that could cause Co2 to make bubbles expand or rupture.
Nevertheless, I had lecture bottles of pure Co2 and nitrogen
available to me when I was first experimenting with Enviro-Tex
coatings, and I tried flooding bubbles in the coating with direct
streams of C02 and nitrogen. There was absolutely no effect on the
bubbles. However, the more conventional process of applying mild heat
from a heat gun or hair dryer (at LOW VELOCITY) instantly pops the
bubbles and allows the heat-thinned epoxy to flow back into the low
spot created when the bubble pops. Remember, we're talking about
bubbles smaller than the head of a pin. I also tried vacuum
de-gassing of the mixed resin, which works very well while the liquid
is still in the mixing container, but I still found that bubbles were
generated when pouring the resin onto the coil form and smoothing it
out with the brush. In the end, I stopped vacuum degassing as an
unneeded complication.
3. Smell:
Terry found the smell disagreeable enough to recommend the use of a
fan during application, I suggest applying the coating in a
completely sealed, draft-free room. The uncured material does have a
distinct "epoxy resin" smell, but I didn't find it objectionable. My
reason for suggesting a damp-mopped and draft free room is to
eliminate (as much as possible) any lint or dust in the air. This is
to eliminate any dust from settling on the coil while the resin is
curing. Dust and lint settling on the coating will leave nearly
microscopic (but still visible in the right light) little lumps and
bumps in the coating, just like they will on a varnished coil. It
just depends on how much of a perfectionist you are. Because of how
perfectly glass-smooth the rest of the surface is, any little dust
motes or lint embedded in the coating stand out visually. Regardless,
any lint that does get embedded can be easily sanded out with very
CAREFUL use of #400 or #600 grit silicon carbide "wet-or-dry" paper,
used wet with a little dishwashing detergent added to the water as a
lubricant. After final sanding with #600 paper, the epoxy can be
polished to a high gloss using any polish designed for acrylic or
polycarbonate, or even just an automotive type polish.
So, there you have it: really very few significant differences
between Terry's and my processes. Like anything in Tesla coil
construction, you will need to develop your own application process,
based on the experiences of others who have tried it and recorded
their results. I can absolutely guarantee that anyone who has the
skills to build a functioning Tesla coil will get better results with
an epoxy coating than with a multi-layer varnish coating.
Regards,
Scott Hanson
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Saturday, July 01, 2006 7:43 AM
Subject: Re: Envirotex Lite coating tips
Original poster: Mddeming@xxxxxxx
Hi All,
Since the two people with expertise in the use of Envirotex
Lite (Terry and Scott H.) seem to disagree on a number of key
issues concerning its application, I think therefore that I will
stick with polyurethane until enough trials (disasters?) have
occurred for a consensus to emerge. ;^)
Matt D.