Good Epoxy for Secondary Coats and Maybe Encapsulation

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Kevin Ottalini by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ottalini-at-mindspring-dot-com>

All:
    Tap Plastics sells ETI Ultra-Glo in a variety of sizes and it looks like a
winner
both  in application and finish and price for TC work.  It also has low
shrinkage <1%.
 
I did my 8.5"x48" secondary with only minor mess (my fault) and Mike Loftus
just did his 6.5" x 24" secondary successfully and is putting additional coats
on.
 
It makes a clear thick beautiful finish with few if any bubbles.  It has a good
30minute to 1 hour pot life and self-cures (no heat needed) at reasonable room
temperatures and humidity.
 
Tap can ship the epoxy UPS ground (you can place orders online) and the
prices are pretty reasonable:
 8oz  kit for $     5.45
16oz kit for $     9.50
32oz kit for $   15.85
1 Gal kit for $   46.70
2 Gal kit for $  86.50
4 Gal kit for $148.00
 
(all $USD)
 
As you can see, the smallest kit is probably good for at least 3 or 4 coats if
you don't waste much on a 6x24 secondary.
 
<http://www.tapplastics-dot-com/fiberglass/epoxy_resins/160_ultraglo.html>http:
//www.tapplastics-dot-com/fiberglass/epoxy_resins/160_ultraglo.html
 
Good Resin Comparison Chart:
<http://www.tapplastics-dot-com/techinfo/index.html>http://www.tapplastics-dot-com/
techinfo/index.html
 
(Also a nice little PDF about drilling plastics at the same link)
 
ETI is the original MFG and there is great info about how to use this
epoxy on their web site:
<http://www.eti-usa-dot-com/consum/ultraglo/utlraglo.htm>http://www.eti-usa-dot-com
/consum/ultraglo/utlraglo.htm
 
(note:  their area estimates are way off for this application ... do your
own testing for your application ... 7oz covered about 8.5sqFt for me).
 
There is a real wealth of information about plastics and materials on the Tap
page, so be sure to go to the home page and use the search for specific things.
 
Here is a little basic program to calculate how much you need (approximately).
 
The area estimates are based on how much it took for us to coat our
secondaries.
(Note: your application may be different so don't think this calc is perfect
and blame me if you make too little or too much!)
 
10 PI=3.141592657#
20 INPUT "Enter the diameter of the tube in inches:";DIA
30 INPUT "  Enter the length of windings in inches:";LENGTH
40 CIR=PI*DIA
50 AREA=CIR*LENGTH
60 PRINT "    You need enough epoxy to cover ";AREA;" square inches
(";AREA/144;" SQ ft)"
70 PRINT
80 PRINT "Assuming an average of 1.6 grams per 10 square inches"
90 PRINT USING " you will need ####.# grams or ###.# oz of epoxy per
coat.";AREA*.16, 1.6*AREA*0.0035275
I also let some of this epoxy set up in a cup and will be doing HV testing on
it next week.
 
Like all exothermic epoxies it gets HOT if you try to cast too large an amount
at one time
so use a number of thin (1/8" to 1/4")  layers when potting, not just one big
blob.
 
I'll let the list know what the KV/inch leakage is as soon as I have the data.
 
(hehe I don't work for Tap, I just love that place!)
 
Best,
    Kevin