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Would you recommend using the valspar primer on the internal airframe spars. I'm starting my sonex looking for advice

Thanks

Primer is sort of an eternal debate among builders. Given the corrosion resistant nature of 6061 aluminum, many builders don't use any primers when building. In fact, the factory will generally tell you that, unless you live in a saltwater area, primers simply aren't needed.

In any case, some builders will choose to prime surfaces and use anything from NAPA 7220 (or similar) self etching primer to products such as Valspar. Some will prime all internal parts, while some only prime mating surfaces and flanges.

Ultimately, it's up to the individual builder what they'd like to do.

Ditto what Mike said. I do not live near the sea, and I am not priming my airframe.

The airplane will outlast your grand kids. Save the weight. Leave it bare inside!!


Joe
"Fortes Fortuna Adiuvat"

Thanks guys going without it

Joe

As I've mentioned before, the only reason I prime is resale value of the airplane. i know it's not necessary, you know it's not necessary, a potential buyer with no knoledge about the corrosion resistance of 6061 aluminum vs. 2024 might not.
I know for a fact that pretty much every builder in my SAAA chapter (most are RV builders) would just not believe you if you tell them a Sonex does not need to be primed.

I was restoring a 1946 C140. It is 20 years older than I. It did have some corrosion issues. Not bad for 65 years of service. I bet it spent a lot of time outside. Early in its life it was a college flying club airplane. It had not a lick of primer though it was built out of the same 2024-T3 as an RV. It is possible my Waiex will have corrosion issues in 65 years, though I will hangar it. I will be 112 then.

Weight and time are our enemies. Weight for performance, time because we only have so many years. I want to finish and fly my Waiex so I can go to the next airplanes. I don't plan to sell it.

I always like this debate. There is no wrong answer. Strive to make the choice that makes you happy!

Edit: on the 140 I was a nut about priming everything I put back together. Especially where the cladding was in bad shape.

Here is that 140. Had the wings all the way apart. Replaced the aft spar on one wing. In a restoration there is no joy like the joy from knowing there is primer between mating parts.

thanks bryan looks good

No problem! Not a lick of primer on my Waiex. It is a liberating feeling.