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Old 10-05-2018, 09:50 PM
DanH's Avatar
DanH DanH is offline
Join Date: Oct 2005
Location: 08A
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Originally Posted by RV10Pilot View Post
Do you have a recommendation for a low viscosity epoxy?
I've used a lot of System Three Clear Coat. Great for sealing fiberglass and aviation plywood.
Dan Horton
Barrett IO-390
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Old 10-05-2018, 09:52 PM
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Wunderon Wunderon is offline
Join Date: Jun 2014
Location: Seattle (Edmonds) and Iowa
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Originally Posted by DanH View Post

See this thread; first example is a step by step.
Dan, I want to thank you for resurrecting your older images. I really missed them when they were in photobucket lost land and Iím sure it was a pain to move them and re-link.

Dave Grimmer
RV8 N46LG for Lynda
Edmonds WA
paid 2019
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Old 10-08-2018, 11:13 AM
psalys psalys is offline
Join Date: May 2017
Location: Eugene
Posts: 34

Thanks Dan.
RV-12iS complete and flying
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Old 10-16-2018, 09:50 PM
WingsOnWheels WingsOnWheels is offline
Join Date: Mar 2009
Location: Plano, TX
Posts: 1,771

For minor pinhole filling, I found a finishing filler from the local auto-paint jobber worked extremely well. It is a polyester product, but is being sanded off anyway. It is a lower-viscosity filler that can be squeegeed on and cures fast.

I then used a 2k DTM (direct to metal) High-build primer. That primer is an epoxy hybrid that has the anti-corrosion properties of epoxy in a filler format. Pure urethane filler/primers are not recommended for bare metal and are supposed to be applied over an epoxy primer. In traditional auto body work it is: bare metal, epoxy primer, body filler/repair, high-build primer, block sand, primer-sealer, topcoat system.

Since my windscreen fairing interfaces with a metal surface the 2k DTM was the most appropriate. For all fiberglass surfaces, the dtm is not required, but works fine.
Colin P.
RV-6A #20603
Complete 5/10/19
I donate every year on my B-Day (in Dec), but donated early in Sep'19.
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Old 10-16-2018, 10:14 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 3,991

Originally Posted by Kyle Boatright View Post
You can slightly warm the West epoxy. A few degrees will help. Use slow hardener...
Several years ago, I finished a sailboat wooden tiller that way. I heated it to 140 F and took it out of the oven and let it cool for a couple of minutes so the epoxy wouldn't harden on the surface. Then I painted it with West and slow hardener. As the tiller cooled, the epoxy was drawn into the pores.

The process worked quite well. It took three or four coats of epoxy applied that way before it quit soaking up epoxy. For you boaters, I then put on several coats of exterior varnish - that tiller looked good. But it was too slippery. Don't imagine that would be a problem with a cowl.

Perhaps bagging the inside of the cowl, warming it with a hair dryer or small space heater - being careful to keep the exterior temps under say 150 F - and applying the epoxy would work. Once the epoxy is on, shut off the heater and remove the bag. By then the pinholes should be filled (the fiberglass isn't wood), as the epoxy is drawn in slightly.

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Old 10-17-2018, 08:36 AM
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DanH DanH is offline
Join Date: Oct 2005
Location: 08A
Posts: 8,889

A water-viscosity epoxy as a seal coat...

I was asked to fabricate and install larger tire clearance blisters in a set of Falco gear doors. First task was to fabricate a form defining the shape of the desired blisters. Easy enough; ordinary 2" pink foam from the big box store, a little micro, and one wet coat of System Three Clear Coat.

When cured, sand it slick without breaking through the skin.

It was the waxed twice and sprayed with PVA. Two plies of 9oz 8-harness were laid up over this form, cured, and popped off. Another squirt of PVA, another layup, and I have two blisters with excellent shape.

Next task was cutting the old small blisters out of the gear doors. The new blisters were bonded into place, and two more plies of 9oz were laid over the assembly, followed by sanding to fair it all together. One coat of micro for fine contour, finish sand, then bring out the epoxy coat to seal it all. End result is a 4 ply blister on a honeycomb door panel, nice and light because there isn't a whole lot of filler on it:

The sealed doors were sanded slick, just like the pink foam form. I don't remember if I shot them with PPG K-36 or not. I would have if they had shown some very fine ripples or waves when looking across the surface at a low angle. That's the purpose of filler-primer...flattening any surface contour flaw by block sanding. However, if all the work up to that point was done with an eye toward not creating waves in the first place, it's possible to go directly to epoxy primer and finish coats.
Dan Horton
Barrett IO-390

Last edited by DanH : 10-17-2018 at 08:40 AM.
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