Did you paint your fuselage stringers?

[efwd]

I used an HVLP from Harbor Freight. Very small gun not quite an airbrush but for $8 on sale it was a steal. I did all the wing parts with it as well. I have two of them thinking it was going to plug up but it worked pretty sweet. https://www.harborfreight.com/air-to...gun-62300.html
I guess you would have to get a compressor also if you don't have one. I don't know why you couldn't use an airbrush though for that small amount of work.
Eddie

[rv9ralph]

When I was working on my RV9 project, I primed everything in the beginning. I used an airbrush. The advantage with the airbrush was reaching in the inside of flanges. You could get to the inside of bend without heavy buildup on the flanges. You just needed to make more passes to get good coverage.

Back when Cessna started to use Polyurathane paints, the used a conversion coating (alodine) to protect the aluminum before they painted. Their process did not allow the conversion coating to completely dry, causing filiform corrosion to form under the paint several years later.

Several things to consider when priming. First, primer is designed to be used under a finish coat to assist with adhesion to the material. Because of this primers are usually pourous. This will attract and adhere dirt and moisture. Be sure to use a product that does not do this (epoxy type primers usually will meet this requirement).
Another thing to consider with primers, is if the surface of the material is not properly prepared the primer will not stick (I have seen primer flake off). If this surface is what you will be adhering the fabric to, the bond of the fabric will only be as good as the bond of the primer to the underlying material.

Just some thoughts.

Ralph

[David47]

Agree with Ralph. The comment about surface preparation in particular is fundamental and this applies to both paint adhesion and in the case of bonded joints, adhesive application. I've seen paint just rub off after being applied with no or incorrect surface prep and adhesive develop about 1/4 of its shear strength for the same reason. From a previous life, we used to do Alodine followed by epoxy prime. That's the practice I'm following for my build.

[Cherrybark]

Well bother. Happily, I still have a little Poly Fiber Epoxy Primer left over from painting the spars and trailing edge strips. Wish I had though of painting the stringers before pouring out the left over, mixed product.

[efwd]

From what I read, a zinc based product is more preventative against the filiform corrosion anyhow. I can say that if you use a heat gun to dry the zinc chromate so that you can get the aluminum painted more quickly, the paint and zinc chromate will pull right off with simple masking tape.