The art of pinhole filling

[LettersFromFlyoverCountry]

I'm curious how many "rounds" most people go with pinholes in the process of getting their cowling finished.

I followed the Van's instructions and thinned epoxy and brushed it on, sanded, added SuperFil, sanded, rolled on three coats of Smooth Prime, sanded, filled some more with SuperFil and I'm about to sand again.

I don't have THAT many pinholes, as near as I can tell, which is difficult because Smooth Prime is white. I just sprayed on some cheap dark primer just to get a better look. And now I'll go over it with a magnifying glass after I sand that off, add more SuperFil, and a couple more coats of Smooth Prime.

Still, it feels like this is only a fraction of what I sense most people are doing.

What's your experience?

[rjcthree]

I had three apply/sand out, but I was dealing with excessive honeycombing of the surface too. I did have to do a spot fill after sanding out my first primer filler, exclusively on my mods for the H2AD bumps. Just sprayed coat 2.5 (a spot touch up where I sanded through due to carelessness- and beer) andthat's it - the top is ready for paint. SW Spectraprime (a 3k). One hint - don't prime in direct sunlight, it won't lay down, lol.

Rick

[Lars]

I tried Dan Horton's technique on my upper cowl (the only pinholed part I've attacked so far). Squeegeed on a thin layer of West Systems epoxy, followed by 2 more layers each before the previous layer set completely- within an hour or so, from memory. Then wet sanded. Zero pin holes afterward. Very easy, no special fillers required.

Dan revised his technique using System 3 Clear Coat epoxy and a nappy roller. I bought some to try myself, but I haven't gotten to it yet.

Dan's techniques are described in threads here somewhere.

[KTM520guy]

I do a complete set of RV fiberglass parts in 2.5 days, ready to paint. My steps.

1. Sand everything
2. Fill any pinhole you can see
3. High build prime
4. After primer dries fill any pinhole you can see
5. Spray on a guide coat. Cheap Krylon works great for this.
6. Sand everything
7. If you have only done this once go back to step 2. If you have been through this twice you can skip to step 8. If you think your parts need it do everything again. Can't hurt.

8. Paint

This works for me, YMMV.

[gbrasch]

Bob, I think they are going to have a forum on that at Oshkosh

[BillSchlatterer]

Pretty simple. Roll a coat of slightly thin epoxy on bare cowl. Let dry, sand, and then rub on a light coat of Loehe Pinhole Filler (Axho(?) also makes the same product).

It goes on like a white car wax and fills the pinholes. Let it dry and wipe it off. Then apply coat of preferred epoxy primer, high fill if you have it. The pinhole filler is an epoxy base product and reacts with the epoxy primer as it drys. No pinholes after that. Kinda magic.

Not sure Loehe is the place to buy it any more but there are several paint vendors who make a similar product. Probably all the same and just relabeled.

Bill S
7a 56.2 hours since Jan 1
Still got the grin

[LettersFromFlyoverCountry]

Originally Posted by gbrasch

Bob, I think they are going to have a forum on that at Oshkosh

I think you made a mistake there. Where you typed "infomercial," it came out "forum."