Did you paint your fuselage stringers?

[PapuaPilot]

I bought my plane second hand when it was about 14 years old. I don't know when the first owner painted the stringers, but there was filiform corrosion on them, under the hand brushed epoxy paint. I sanded them and repainted the stringers with epoxy primer. The first owner lived near Salt Lake City and the California coastline.

Like others have said it is about preventing corrosion.

[N213RV]

As another data point, I also primed mine with epoxy primer.

[efwd]

Ok, now I know more than I ever cared to know about filiform corrosion. How can you possibly build these without learning so much. Of course you just not become a member on a forum like this. Awesome.

[Esser]

I did not paint my stringers. However, I did epoxy prime in and out of the spars.

[southwind32]

Has anyone used an airbrush to shoot epoxy primer? I was thinking about giving it a try just to do the 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