Re: [TCML] Envirotex Lite , High Torque drive

["Brian" <brianv@xxxxxxxx>]

[Brian] I was reading the post regarding the Envirotex Lite coating and
after a little research I came across this post, Looks like Scott Hanson was
the original poster and it explains the process of using that type of
coating and is quite informative:


[Brian] Original poster: "Scott Hanson" <huil888@xxxxxxxxxxxx>

Terry, all -


I have used Envirotex-Lite for coating secondaries since 2000, and have
developed a process that works very well for me. I posted this procedure
once several years ago, but I couldn't find it in the TCML archives, so here
it is again: 


The epoxy material I use is "Envirotex-Lite", and it's advertised as a
"pour-on" coating. The manufacturer is Environmental Technology, Inc, and
their website is www.eti-usa.com. 




There are a large number of consumer and industrial epoxy's that are
suitable for coating secondaries, but this particular one is carried locally
(So California area) by the Ace Hardware chain at a reasonable price. There
are several different "kit" sizes; the quart kit contains enough material
for at least (4 ) 6" X 30" secondaries. 




(Here is a process for applying epoxy coatings that I have posted before,
but may be of use again as there seems to be a renewed interest in using
these coatings for secondaries): 




I strongly suggest that anyone who is contemplating coating a finished
secondary, and can cobble up any type of a motorized "rotisserie" device to
keep the thing turning at slow speed, consider using a two-part epoxy
instead of any type of solvent-based coating (varnish, Glyptal, etc). I
recommend a DC gearmotor with an adjustable speed control; this allows you
to set the optimum surface speed regardless of secondary diameter. 




Having coated at least a dozen secondaries with epoxy, I can assure you that
NO solvent-based coating can remotely begin to compare with the appearance
of a correctly-applied epoxy coating. First of all, a single "light"
application of epoxy provides a cured coating thickness of at least
.030"-.050". It would take many, many coats (dozens!) of varnish to generate
a similar thickness. The total "wet-time" of these multiple coats is many
times that of the single coat of epoxy, greatly increasing the time that the
coating is susceptible to picking up dust, etc. 




Because the epoxy stays "syrupy" until it starts to jell, you can flow on a
heavy coat very quickly, then allow the coating to "self-level" while
rotating. This results in a finished secondary that appears to have the
windings encased in a glass sleeve. Any type of solvent-based coating begins
to lose solvent, thicken, and skin-over the instant that the lid is removed
from the can. It's impossible to "level" the entire coating on a coil at
once when using a solvent-based coating. 




In the end, the coating ends up being LESS costly then a varnish coating!!!
I have used a 1 quart kit (2 half-quart bottles) to coat (2) 6" X 32" coils,
(2) 3.5" X 20" inch coils, (1) 4" X 12" coil, a 2" X 5" coil, and at least
two others. Add the paint thinner, rags, quality brushes, etc, etc, required
apply multiple coatings of varnish, and I guarantee it exceeds the cost of
an epoxy coating. I think my 1 quart kit cost $17.00 at Ace Hardware. 





Tips:




1. Set up a completely dust free, draft free area to work in. I use a
bathroom, damp-mop everything, close all windows, etc, etc. A carpeted floor
is useless; any movement stirs up a cloud of fibers. 




2. Very thoroughly wipe down the completed coil with a clean cloth moistened
with 90% isopropyl alcohol to remove any trace of oil from the windings.
Even fingerprints may cause "fisheyes" in the completed coating. 




3. After all traces of solvent have fully evaporated, I do a very careful
wipedown with a cabinetmaker's "tack cloth" to pick any residual lint or
dust. 




4. Carefully calculate the volume of material required, based on a thickness
of .040" or .050". Always err on the high side. I know the panic of having
to mix up another ounce to finish the last inch of an almost perfect
secondary. As a portion of the coating will "wick" down into the windings,
the final coating thickness will be less than .040" or .050". DON'T TRY TO
APPLY TOO THICK A COATING! Even with the spindle turning at a very low
speed, circumferential rings may develop on the OD of the coil. At first it
may seem that there is not enough material to completely cover the windings,
but continue to spread it with the foam brush. Add more coating only if it
is impossible to get coverage. 




5. Mix VERY thoroughly in a meticulously-cleaned, completely dry container;
glass is preferred, and DON'T use a waxed paper cup.. Use a clean piece of
wooden dowel to stir. I end up with a froth of bubbles, but they seem to all
pop during the coating application. 




6. Turn on the spindle drive motor & adjust speed to about 5 RPM (depending
on the diameter of the secondary). LEAVE THE SYSTEM RUNNING UNTIL THE
COATING IS COMPLETELY CURED! (4-6 HRS). 




7. Position a 3-4" wide disposible FOAM paintbrush (NOT a bristle brush)
against the top of the secondary, and start pouring a very thin stream of
liquid immediately in front of the brush. The first rotation will only
spread the liquid slightly, getting better coverage with each turn. At this
point, the brush is being used as a squeegee. Reduce your movements to avoid
stirring up dust & lint; stand in the same spot without walking around. Have
all your tools and materials laid out in front of you at arm's reach. 




8. Get an initial spiral of liquid applied from end-to-end of the coil, then
go back and spread it into a uniform coat.8 




9. As the coating flows together, reduce pressure on the brush until it is
barely contacting the surface of the coil. 




10. Keep the coil rotating, and inspect for tiny pieces of lint, etc. Use a
pin to lift them from the surface. Stop the rotation only long enough to
remove the lint. 




11. By this time, 99.99% of the bubbles should have disappeared. Use a hot
air gun to sweep areas with any remaining bubbles. DO NOT HEAT THE COIL!!!
Invariably there is air trapped under the windings. Applying excessive heat
will cause this air to expand and bubble out into the coating. The hot air
gun temporarily thins the very top layer of the coating, and at the same
time causes the air in the bubbles to expand. Most of the remaining bubbles
will pop by themselves. Finally, use a pin to pop the last few remaining
bubbles, if there are any. 




(The use of carbon dioxide to cause the bubbles to pop is a myth. There is
no physical or chemical reason why CO2 should cause the bubbles to pop. I
tried directing streams of pure CO2 and pure nitrogen on early coils I
coated, and the gas had no effect on bubbles. However, mild heat from a heat
gun or hair drier works instantly. The heat causes the viscosity of the
surface of the epoxy to decrease instantly, and the heat also visibly
expands the bubbles. Someone has also suggested the use of a propane torch;
this is ludicrous.) 




12. Inspect the coil for bubbles, pinholes, lint, thin areas, etc. When
satisfied that everything is perfect, slowly walk out and VERY SLOWLY close
the door. Make sure no one opens the door until the coating is fully cured. 



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