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Re: Coating Secondary with Epoxy



Original poster: "Scott Hanson by way of Terry Fritz <teslalist-at-qwest-dot-net>" <huil888-at-surfside-dot-net>

Dave -

According to the rather limited data available from TAP Plastics, the
Ultra-Glo "polymer coating" is a finish resin and not a laminating resin,
which means that it should not have any residual tackiness after curing.

I have used epoxy resins for many years for coating, insulating, and potting
purpose. In my experience, the most likely cause of tacky "patches" is
inadequate mixing of the resin and hardener, leaving hardener "starved"
areas. If there was a fundamental problem with the ratio of resin to
hardener, or if the hardener was "old", the entire surface would be tacky.
Thorough mixing of the resin and hardener is especially critical with
transparent epoxy systems, where it is visually very difficult to determine
when the two components are properly mixed. To get adequate mixing, you will
usually end up with a large amount of entrained air bubbles. To minimize
bubbles in the coating will require that the mixed resin be vacuum degassed,
which can be done even with a small automotive hand vacuum pump.

A less likely cause is contamination of the resin with oil, grease or other
material from the mixing vessel or from the secondary itself.

Trying to sand the tacky spots is usually futile as any abrasive paper will
clog instantly. I'd set the secondary outdoors in the bright sun for several
days, and see if the ultraviolet in the sunlight, plus the warmth, will help
finish the cure cycle. If this doesn't work, you can try adding a third
coat, but there's no guarantee that whatever's inhibiting full cure of the
second coat won't propagate through and affect the third coats also.

Scott Hanson
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, January 05, 2003 12:48 PM
Subject: Coating Secondary with Epoxy


 > Original poster: "Dave Leddon by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<leddon-at-attbi-dot-com>
 >
 > Hi Folks,
 >
 > Last Thursday I coated a 10-inch secondary with Ultra Glo, an epoxy sold
by
 > Tap Plastics, and Friday I applied a complete second coat to cover several
 > areas that came out a little thin.  Now, 48 hours later, I've still have
 > several small areas which are tacky to the touch.  The product literature
 > claims a complete cure after 24 hours at room temperature so I suspect
that
 > this stuff has cured as much as it's going to cure.  Any ideas on causes
 > and treatment?
 >
 > Thanks,
 > Dave
 >
 >
 >