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Primer for cowling and fiberglass parts

Triumph1974

Well Known Member
Hi Everyone, i am likely going to primer my cowling and the other fiberglass parts this Spring with a White primer....for UV protection....I will paint maybe in the fall or next year. Would like to find out the following.

How much primer is typically used when doing these parts? (Need to buy an entire gal.)
Any recommended paint brand/ system? Was thinking about using PPG brand.

Thanks, Paul

Rv7a
 
shot my cowl (outside only), windscreen fairings, and empennage tips so far with PPG DPLF.

Still have pants, legs, and wingtips to go but looks like a quart will
be enough (2 coats).

or very close to enough I hope $$
 
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Pinholes, baby!

If you are gonna try to fill the pinholes, a 2K filler/primer will be the best tool. I use a 1?x4? foam roller to put the stuff on, then sand most of it off & repeat as necessary - the last coat should be sprayed on. One the entire surface is good, you can spray on the epoxy primer.

I also use PPG for these chemicals, but I buy Shop Line - their second line products.

Keep in mind that even the epoxy primer is not UV proof - adding a topcoat of paint is recommended.
 
Mark is right..you really should address surface filling (pinholes and little defects) before spraying primer. There are multiple ways to seal the surface. I like an epoxy skim, Mark likes 2K urethane high build, other like wipe-ins like
Akzo Nobel 28C1, and the latest proposal was drywall mud.

I use West 105 when I want higher viscosity, and System Three Clearcoat when I want a water thin coating. The local GKN facility uses epoxy/cabosil, as does a prototype guy I interviewed recently.

Squeegee on, back and forth to work it into the pinholes, then run a roller over it to leave a orange peel finish as a sanding guide. After cure you just sand until the orange peel is gone and no further. Do not break through to the fiberglass surface or you'll open new pinholes.

Search "pinholes".
 
Mark is right..you really should address surface filling (pinholes and little defects) before spraying primer. There are multiple ways to seal the surface. I like an epoxy skim, Mark likes 2K urethane high build, other like wipe-ins like
Akzo Nobel 28C1, and the latest proposal was drywall mud.

I use West 105 when I want higher viscosity, and System Three Clearcoat when I want a water thin coating. The local GKN facility uses epoxy/cabosil, as does a prototype guy I interviewed recently.

Squeegee on, back and forth to work it into the pinholes, then run a roller over it to leave a orange peel finish as a sanding guide. After cure you just sand until the orange peel is gone and no further. Do not break through to the fiberglass surface or you'll open new pinholes.

Search "pinholes".

What type of roller are you using to roll over it?
 
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Cowl prep

What type of roller are you using to roll over it?

Thanks Dan, After I installed the cowling, I did the pin hole fill procedure per the Vans book with brushing on thin West expoxy, but I probably will sand it and then do your squeegee and roller method to ensure I get all the pin holes and have a good sand marker with the orange peel roller surface. Thanks for the ideas!
 
Thanks Dan, After I installed the cowling, I did the pin hole fill procedure per the Vans book with brushing on thin West epoxy...

Thinning epoxy makes no sense. There are very thin resins available if desired, but conventional viscosity works fine. The idea is to build a mil or two of thickness, a shell of sorts.

The real downside is ad hoc chemistry. Mix a 50 gram batch. Pour off half into another cup. Now add a solvent thinner to one of the cups. Compare in three days.
 
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