MartySantic

MartySantic

Well Known Member
How are you going to prepare the fiberglass components like the empennage tips, the tailcone and cowling for final paint.

There are two types of fiberglass in the kit One is epoxy glass. And the other is a glass that has been gelcoated. I would guess the prep method for be different for each type.

Looking for the best method to eliminate any of the pinholes.
 
Hi Marty. I have done quite a lot of fiberglass work in the past on boats and such, so have my own techniques that I could pass along. However, I am very interested in any replies the other "experts" on VAF might have specifically for aircraft fiberglass work.
 
primer

Hi- I have had excellent results with the Randolph rand o plate(dark green) epoxy primer. If you have pinholes, as long as they are not too large, prime first, fill pinholes with catylyed automotive spot putty, and reprime with Randolph. If necessary you can use a heavy buildup to fill minor flaws in the fiberglas. This should work fine over poly or epoxy glass. Scratch every thing up with 120 sandpaper before priming and sand between coats with 180 wet. For white topcoat, use some light grey primer between the Randolph and the topcoat. PPG grey green epoxy is ok but does not fill defects as quickly and will require more coats.
 
I used UV smoothprime with good results. It fills pinholes and is compatible with all eurethane paints. It can be applied with a high density roller or sprayed. However it takes a couple applications of about 3-4 coats. Each coat dries in about 20-30 minutes and a lot of sanding - just to fill pinholes. Another option I wish I would have tried is the Loehle aircraft finsh system. They have a pinhole filler called 'wonderfil'. My business partner used this and it was very easy. You just wipe it on with a cloth - it's like car wax and goes on like car wax - wait until it hazes over, and then just wipe it off. That's it, pinholes filled! Least that's what their advertising says. In truth you may have to do that a couple times, but it doesn't take long. Then their sandable primer system is pretty messy (sanding dust) like all sanding primers, but works well too. Check it out at their website and call:

http://www.loehle.com/

Tell the lady Scott Hersha referred you...

Scott
 
Wonder-Fil appears to be Akzo Nobel 28C1, an industry standard, although only Loehle knows for sure.

http://www.anac.com/products/DataSheets/28c1.pdf

You should be able to order it at the same place you ordered Akzo primer, or:

http://www.anac.com/about/worldwide_n_america.asp

I'd be pretty comfortable with an Akzo product applied and overcoated per the TDS. However, simply filling pinholes doesn't get most parts paint-ready. Your Van's cowl, for example, will probably have a few surface contour issues; low spots, divots, edge matching, etc. You also want to make sure the honeycomb pattern doesn't print through the finished product, so some surface thickness buildup is desirable. A wipe-on pinhole filler does neither. Low spots and divots require a hard filler, while surfacing and build requires at least a primer-surfacer.
 
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Dan
Does the epoxy primer have to be the same brand as your finish paint? I've been using the Randolph, Rand-o-plate green mentioned above for the interior and was thinking of using it on the exterior. With a white finish paint should I switch to the Randolph white primer? What are you refering to as a surfacer in your last post? Soon be time to begin this process, just finished up mating the cowl to the Fab. Forgot to mention I'm building a 10, as this is in a 12 forum, but filling and sanding is still the same on both.
Thanks Ron
 
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<<Does the epoxy primer have to be the same brand as your finish paint?>>

No, but. I think epoxy primers as fairly benign. Other stuff isn't.
 
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Lots of information

There is lots of information out there, do a search on this site and you'll get lots.

Regarding the gel coated parts, the big issue is voids. My process involves block sanding with 100 grit paper to really get into and remove much of the gel coat. When you do, you'll find voids and worm holes everywhere. If you just sanded lightly, primed and painted the voids would eventually break through.

Once you "open up" the gel coat, you can do the appropriate fill job.
 
sanding UV Smoothprime

Group...
How much of the UV Smoothprime should be sanded off? I rolled the first 3 coats on the cowling over the weekend and sanded last night. The directions on the Poly web site indicate to just sand until relatively smooth, then apply the second group of 3 coats.

I sanded a couple spots down to where I could see the original pink color of the cowl and it appears that the white smoothprime is embedded in the pin holes. Do you sand back to this level of leave a couple mils of the smoothprime on the surface.

I'm using Superfil to fill in any deeper holes and build-up's / leveling that's requried. Works fairly well. Just teaches you much patience and humility :)
 
I just finished my wingtips (RV-6) which included adding mounts for position lights. I rough sanded using 80 grit then I applied a resin wipe. This is West Systems epoxy resin applied with a squeegee or foam brush. Sanded with 230 grit then primed with urethane high build primer. Had 3 pinholes on one tip and 2 on the other and some imperfections. Used lacquer putty to fill holes and imperfections then primed again. Sanded for paint. Paint looks great!

Ken
 
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