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Poly Fiber UV Smooth Prime Questions

Brett H

Active Member
Since I am planning on flying before external painting, I am attempting to use Poly Fiber UV Smooth Prime to fill in the pin holes in my fiberglass parts prior to spraying a coat of primer and I have several questions.

I can get the pin holes filled by squeeging in the first coat and then rolling on the additional coats.

The rolled on coats have a rough texture and require much sanding to remove the texture. I have tried several different foam rollers and a short nap roller. Some are smoother than others. But, none are very smooth. Any suggestions on to minimize the texture of the dried surface?

When sanding the coated surface, I am unable to leave a white coated surface everywhere. Namely, in some areas I am exposing the filled in fiberglass. Is this acceptable to have these exposed areas? If not, how does prevent sanding through the coating in some areas?

Your assistance would be appreciated.

Thanks.

Bret Herrick
Columbus, IN
Finishing the fiberglass pieces on an RV-12
 
Micro

No experience with Poly. The trick is using different colors of product. Micro is white. Gray primer over that. Another color if needed. The idea is to block sand and never go past the bottom color.
I prefer Dan's method.
Apply micro. I actually modify this step by thinning the micro 10% with denatured alcohol. Work fast. It evaporates quickly but the thinner micro is easier to apply an even layer. It also allows more micro in the mix. The final product sands really quick. Easy to get flat.
Block sand flat. 40 grit to remove irregularities then 80 to get it optically flat.
Apply two skim coats of neat epoxy 30 minutes apart. This fills and seals pin holes. Feel free to roll. The roller imparts a texture making the final sand easier to see.
Wet sand the epoxy till the texture is gone.
I think Dan uses a high build primer. I apply two coats of gray 2K epoxy mixed neat. No reducer. Brush or roll on per manufacturers recommendation.
Wet sand flat 220.
Spray white or black primer
Wet sand 400-800
Full imperfections with glazing
Wet sand
Spray final
Cut & buff
Sounds like a long process but it's not. It goes pretty quick. Most of the time is drinking beer and watching paint or epoxy cure. :D
 
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I had very mixed results with smooth prime - and will not use it again. But if I did I’d:
- Thin with just a touch of water and use a standard HVLP spray gun. This cut the sanding chore down by more than half.
- Never wet sand smooth prime! If you must allow for three weeks for it to fully dry. This is necessary as the smooth prime retains moisture - and you will find out as soon as you do a pass with your nice epoxy primer.

Carl
 
I thinned with water and sprayed with cheap Harbor Freight gun. Worked great with sprayer. I tried rolling too, and had same frustration as you. WAY more work to sand smooth if rolling.
 
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