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Permalink Reply by Larry Zepp on June 3, 2020 at 11:29am

Hi Greg,

I am getting closer to flying my 650B and have learned a few things about corrosion protection along the way.

• Cortec water based primer (Sold by Zenith) has excellent corrosion protection. I used it on my tail, rudder and wings. Biggest complaint that caused me to switch to Etch primer is the cortec is a soft film.
• The rattle can etch primer (Duplicolor or other in the auto store) provides a good etched bond to aluminum - its major function. But the etch primer is porous to the weather, so it needs a top coat to seal it.
• If you have a paint booth handy, the ultimate is a two part epoxy primer that gets the bond to aluminum and is also a sealer. If the epoxy has Zinc Chromate, it has better corrosion resistance, but you need to keep the chromate (chromium) out of your lungs. Most paint manufactures have stopped using Zinc Chromate.
• I used etch primer on many lap seams in the fuselage and wings as a bonding coat and intended this to be painted over with a two part epoxy. Then several paint system manufacturers said their epoxy would lift the etch primer, which is lacquer thinner based.
• Most experienced builders say don't mix paint brands. I picked Super Flite brand polyurethane and was pleased to find their two part epoxy primer does not have any problem over dried etch primer or dried automotive engine enamel I used in the interior.
• Glad I picked that brand. I have a three stage turbine sprayer and external air source (Polyurethane tries to kill you) and plan to paint the Zodiac in large pieces this Summer.
• Best to get a weight estimate from your paint supplier.
• With all of those Avex pull rivet stems being steel, I swore I was not going to test fly without paint. I have no interest in polishing - then birds would make me paranoid!

Best Regards, Larry Zepp N22LZ, Fort Wayne, IN

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Permalink Reply by Greg O'Shannessy on June 5, 2020 at 4:56am

Hi Larry

Thanks for the info, will check out comparability before progressing.

Part of my question is should I prime the internal surfaces as well as prime and paint the external surfaces.

Thanks again for your help

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