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RV8R999

Well Known Member
As per VAN's instructions, I started the pin-hole sealing job this past weekend using a 50/50 mix of West and Acetone. It goes on very easily but as it began to set I noticed hundreds of tiny little bubbles forming. These set with the epoxy and although most of the pin-holes were filled, these bubbles created their own little pin holes. Sand them all down and recoated. Same bubbles but far less.

Are the bubbles forming as a result of the acetone vaporization?

How many coats did you use till you were done with this? It looks to me it will be about 3 full coats and then maybe a few spot corrections.
 
You might not have waited long enough after the acetone wipe, before applying the epoxy-acetone. It will continue to evaporate right thru the applied coating until it's gone or the coating gets hard.
Painting on epoxy is a frothy mess. However, the air bubbles in mine quickly worked their way to the top and dissapeared. My workshop was about 52 degrees F, and the epoxy set up very slowly.
I did have some remaining pinholes, but I brush coated with PPG DP-50 primer, that took care of it. My paint supplier said to just use the DP primer, but I over did it as usual. I used uncut epoxy in the bottom cowl, and acetone cut epoxy in the top cowl.
 
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It was about 6 hours from when I wiped it down to when I applied the first coat and my garage was about 75 deg. Maybe the epoxy is setting too fast (205 hardener).

Thanks for the tip on the PPG primer. I'll do that.

Ken
 
Regardless of ancient Vans advice, the epoxy manufacturers say do not thin their products. If you want to paint on a thin epoxy (viscosity like water) try System Three ClearCoat. Ordinary West seals well using a more mechanical method like a squeegee.
 
Smooth Prime is good

I used it. Water based. Dries quickly. Easy to sand. Covered it with epoxy primer before final paint.

Michael Stephan
RV-8 N991MS
 
Smooth Prime

I used it on my '9 and it tended to post cure and shrink once the top cowl got good and hot. I no longer use it. My preference is to spread a good quality filler (like Metal Glaze) onto the cowl to fill the craters (not pinholes, craters!), sand it all smooth (mostly all of the filler off), then spray a couple of good coats of PPG K36. This will give you a nice smooth finish (after light sanding) for the paint.

No evidence of post-curing, no adhesion problems, all materials sand well. YMMV. :D

John Tierney said:
At an EAA Sportair workshop the presenter recommended Smooth Prime for filling pinholes. Anyone have experience with this?
http://www.aircraftspruce.com/catalog/cspages/smoothprime.php
Click to expand...
 
RV8R999;
Not to short any of the other contributors here, but I always defer to DanH on epoxy and fiberglass. Although I'm not very good at it yet, everything has turned out well if I read his posts first.
 
Denatured alcohol

You can thin epoxy with denatured alcohol. It does not attack either the resin or hardener. Acetone does.
 
For wiping fiberglass, has anyone tried US Composites Kleer Koat?

I know DanH was using System Three Clear Cote with success, but the price difference is amazing. US charges about $40/gallon for a kit while the S3 product is about $150 for the same volume. I was about to order the stuff from US Composites when I saw this thread and thought I'd ask.

Not worth the savings if the product wrecks all your prep work.
 
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