Corrosion Repair
I have some minor corrosion and poorly painted spots on my Cherokee that my mechanic hasn’t been able to find the time to repair. I thought I’d do it myself so I looked online for instructions. This post is fairly detailed and matches what I’ve read elsewhere.
I would suggest that you strip all the paint off if there is any sign of corrosion. The best method is to use striper, you need to be sure there is no missed areas. Once the panel is bare, the wire brush is ok. On light surface spots bead blasting and Scotch Brite pads work well.
After you have the panel clean and all signs of corrosion are gone. You should use a metal prep and alodine. You can buy these at an aircraft supply or auto paint store. The prep is a citric acid wash, I use fine Scotch Brite to apply it. The alodine is the next step and should be done as soon after the prep as possible. The alodine is sold two ways, I prefer the type that tints the metal, that confirms coverage.
Once the panel is in alodine; you can use an etching primer or zinc chromate, I prefer using an etching primer. Vari-prime or an other good epoxy primer is a better base and the alodine also known as conversion coating protects the base metal. The etching primer is applied in thin coats and you may need to use a filler primer on top of the etching primer to ge a smooth surface.
One last thing; you said it is cold. I painted my airplane one winter here in Los Angeles, it was a record cold winter low 20’s. You need to heat the area where you paint. Painting in temps below 65-70 are hard at best and below about 55-50 the paint will not cure. Heating the paint helps but the panels should be warm or the paint will not flow well. I made the mistake of learning this the hard and messy way. If you can’t do the work until warm weather don’t do any thing. Spray the areas that have corrosion with ACF 50 or other corrosion inhibiter and wait for the right time.
This is the method used in aircraft refinishing and quality auto and truck shops.
I can’t get alodine, but in a previous post, I mentioned that Zinc Chromate is still available, so I’ll use that. Several posts recommend against using steel wool since tiny fibers may remain in the aluminum and rust. They also recommend using a brass brush instead of steel. I don’t know if their concerns are justified, but it can’t hurt so that’s what I’m going to do.
I can also verify that you can’t paint when the temperature is too cold. The paint won’t cure and will just run off.