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Re: Envirotex Lite coating tips
Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>
At 12:17 PM 7/1/2006, you wrote:
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.
:-))) Looks like they are about the same to me, but Scott is just
far better at at.
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.
I was going to try the foam brush next. I see Scott has already
proven it works great ;-))
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.
CO2 creates ammonium carbamates in the liquid by reaction with
atmospheric carbon dioxide which apparently helps boil off or pop
bubbles. However, I imagine that only works so far. Some commercial
places use CO2 gas too... However, Scott reports that just heat
works fine too just like we all suspected ;-))
I did not let the liquid sit and it had a lot of little bubbles as a
"foam" on the surface. It would have been easy to avoid that, but I
didn't. I would think high frequency vibration would be nice
too... But just being careful will probably fix it all easily enough.
Terry found the smell disagreeable enough to recommend the use of a
fan during application
I live in a little apartment so the smell fills the place up fast and
I can't escape ;-)) 95% of the time the smell wound be a don't care.
, 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.
For little coils, one could also fix up a little paint chamber out of
plastic sheeting. But at that point it sort of gets to be too much
trouble to care about. If there is little stuff in there, I can't see it 8-)
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.
I love it!! I would do some things differently the second time, but
the coil worked out great ;-))
Any little bubbles are invisible unless you look really close. The
deep glassy shine is really cool! The coating looks bullet
proof!! Anything that could get through it would probably kill the
wire and form too.
I used to use polyurethane but it takes forever to dry, smells for
months, hard to get thick coats to dry in less than a year... It
also has failed on me due to it not being thick enough and cracking
up. This Envirotex stuff stays sort of "rubbery" so I hope it will solve that.
Do you know what the electrical characteristics are???
Ah... It's "clear" :o))) But I assume it properties are
electrically "nice" like all epoxies.
and how it compares to polyurythene, or varnish, or what DC
recommends. I'm presuming the main advantage of this stuff is fewer
coats and less time for a coat.
Thick glassy coat, fast drying, no smell, easy, and pretty cheap,
non-flammable... The Stuff DC uses is probably the "best". Boat
varnishes tend to dry on the outside but stay wet on the inside in
thick coats, after like 3 years!!! Epoxies are really cool in that
they always dry on time...
Original poster: Mddeming@xxxxxxx
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. ;^)