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Pinhole/epoxy/primer Q

az_gila

Well Known Member
OK fibreglas/primer experts...:)

I'm presently pinhole filling my pink cowl parts with a brush/wipe of West epoxy, and it seems to be working pretty well.

The next step is to paint it with a white epoxy primer and then fly the hours off with unpainted aluminum and white epoxy primer glass parts. A plan cleared with a local paint shop.

I think my first coat of epoxy primer will show up some minor defects in the filling and will need sanding before a final coat.

My question is "what to use to fill the few major defects - such as small gouges - that will show up after the first coat of white primer?

Is there a suitable filler material that can be used between epoxy primer coats?

With all of the epoxy steps so far I don't really want to use the red lacquer based non-catalyzed filler materials.
 
We used the red filler primer that looks like a toothpaste tube to fill all the visible holes. Wet sanded, then used PPG high build primer. Wet sanded, then repeat. Different products vary, but the PPG we used needs to be painted over or re sanded before paint or white primer coats.

Ask the paint store for suggestions with the product you are using. They were very helpful. For the price of the paint, they should have sprayed it out for me!

Did the pics of the lower cowl opening help you any?
 
We used the red filler primer that looks like a toothpaste tube to fill all the visible holes. Wet sanded, then used PPG high build primer. Wet sanded, then repeat. Different products vary, but the PPG we used needs to be painted over or re sanded before paint or white primer coats.

Ask the paint store for suggestions with the product you are using. They were very helpful. For the price of the paint, they should have sprayed it out for me!

Did the pics of the lower cowl opening help you any?

OK, I can try the Toothpastey stuff...

Yes, I forgot to thank you for the pics. :eek:

I ended up making the gear slot 1/4 wider on each side and it seems to have worked out nicely for installation of the cowl.
 
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Please don't use any uncatalized spot putty. It is just super thick lacquer primer. Generally not used by anymore. Shrinks over time. Any two part glazing putty would work better if it is a small area. No lacquer products please.
 
Small nicks I would use the West system with microballons. Larger ones use the West system with flox. Both would be compatible with the future paint.
 
Small nicks I would use the West system with microballons. Larger ones use the West system with flox. Both would be compatible with the future paint.

That was my first thought, but when I did the same on the tips of the tail surfaces the filler seemed to absorb the epoxy primer a bit and was visible if it only had one coat of primer over it.
 
I agree with what was said above, but the red putty was used for the very small pinholes on ours with success. Most of it was sanded off. Multiple layers of thinned west epoxy were placed prior to starting filling pinholes.
As stated before, the spray on 2 part high build primer works well. Takes several coats with wet sanding in between. Before the final paint you will need to sand again, spray the non sanding primer, then top coat.
 
Evercoat 416

That was my first thought, but when I did the same on the tips of the tail surfaces the filler seemed to absorb the epoxy primer a bit and was visible if it only had one coat of primer over it.

Hey Gil,

Get some Ever coat 416 or off brand glazing compound. Great for small blemishes, is catalyzed and sands great.

DO NOT use the stuff in a tube. It will react to many things. You don't want to paint and have a problem later.
 
That was my first thought, but when I did the same on the tips of the tail surfaces the filler seemed to absorb the epoxy primer a bit and was visible if it only had one coat of primer over it.

I used a highlift primer and did not notice any ill effects. There are several spots on my fiberglass that I used the microballons for fill. I make sure that my microballon epoxy mixture is not too dry. It still has a sheen to it. If you add too much microballons the surface turn a matte finish. I found that if it is too dry it would not trowel smooth and fill pinholes adequately.
 
Pinholes

The last microballoon you rupture sanding will be a pin hole in my experience. That said, a two component high fill primer is is a good hedge in your favor .
 
filler

You can also mix the micro in a small quantity of the epoxy primer. That eliminates any issues with compatability.
 
Thanks

Hey Gil,

Get some Ever coat 416 or off brand glazing compound. Great for small blemishes, is catalyzed and sands great.

DO NOT use the stuff in a tube. It will react to many things. You don't want to paint and have a problem later.

Thanks, that sounds just what I was looking for.

I went with the Evercoat 417 which is buff colored with a white hardener since I don't want too much contrast. Should be great for filling those few remaining pinholes and little divots that I am sure will appear after the first coat of epoxy primer. With a 5 day window for re-coating the epoxy primer I should be able to fix the little spots, let the stuff cure well, and then put on a second primer coat without needed an overall sanding.
 
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