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Re: [TCML] Varnish for SSTC secondary




Hi Jay
Yes, I only applied Envirotex while the secondary was spinning at about 4-6 RPM on the lathe. You have to adjust the speed to balance friction and gravity. Generally speaking, keeping some kind of knife edge at a constant distance (also needs to be adjusted continuously at the start) keeps the bulging down.

I do admit the deviation from a perfect cylinder is there. There are annular bulges. I have not noticed them causing any sort of effect on the arcs.

The bubbles that are there during the mixing process all seem to "evaporate" during the spinning/drying. What does happen, though, is that if the coating gets cold, it tends to generate bubbles that weren't there before. The "cure" for those is a heat gun/hair dryer, but of course, only when the coating is still less viscous. There is a point of no return that seems to be around an hour after the initial pour, after which no matter what you do, those bubbles are staying.

The solution seems to be to keep the drying temp constant around 70F/21C. If you can keep that temp for a full day, it works great - no bubbles.

Cheers,
Joe

On 2/1/2013 12:58 PM, jhowson4@xxxxxxxxxxx wrote:
Envirotex lite is great, as long as you have a way to keep the coil constantly rotating and the ability to set the speed.

As far as bubbles go, i have had great luck letting the epoxy sit for a little bit after mixing and then applying it.
when it is applied monitor it for 30min, first using the blade to get rid of bubbles and ensuring an even coat, then using a heat gun to expand and pop them and finally using a needle to get more resilient ones and smoothing with the knife again. The stuff stays fairly pliable for a good long time, on the order of hours.

Things to watch out for are having the speed of your spindle too high or too low. too high and you get annular bulges and too low, well i'm not sure on too low because i have not made that mistake, but i would imagine longitudinal bulges.



Thanks,
John "Jay" Howson IV



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