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Is alodine sufficient to protect alone?

Nashpdman

Active Member
Is alodine alone sufficient to protect the inside of the wings? Specifically without primer or paint, just alodine.
 
Probably

Probably, but priming is easier. To apply alodine properly is quite the process and time consuming. Especially on big sheets like wing skins. It's also quite toxic and contains chemicals we all want to avoid. Disposing of used alodine is a pain, think hazmat. There are much nicer primers out there. Easier on you, me, your neighbours, my kids.
 
yes and no.

My testing in a salt fog chamber, and then outside for a year in coastal FL showed that etch followed by chromic acid conversion (Alodine) held up fine in the salt fog chamber.
It did not hold up as well in the weather.
Etch/chromic acid conversion/epoxy primer was bulletproof.

For that project (RV-4), I only primed the inside surfaces and rivet lines. The project went on hold and I stored the empennage in the garage. After a couple years, the surfaces facing up had pitting corrosion on the bare alodined skins. The accumulated dirt and dust held moisture on the skin (humid FL) and started corrosion cells.

I did the etch/alodine/epoxy primer on my projects since then, but the next one will be simplified to scrub and wash primer. I'm not going to live another 25 years, and my opinion is that any organic coating that keeps the dirt/dust off the metal will help immensely without the huge time investment with the etch/alodine/prime dance. (just make sure you have a complete coating! (sorry Vans))
 
Is alodine alone sufficient to protect the inside of the wings? Specifically without primer or paint, just alodine.

Properly applied alodine will work fine without additional protection needed, assuming no abrasion occurs on the surface. The reason the epoxy primer on top of the alodine works better is due to improved resistance to abrasion.

A good example is your engine case; alodine only will work fine.

Leaving exterior parts alodined...not so much, due exposure over a long time that can erode the alodine and eventually leave the aluminum exposed to corrosion.
 
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