This is why you MUST prime!

[Dozer]

I left several sheets outside my garage for 1 month. Terrible corrosion.

Alclad doesn't protect anything.
It works just to keep the metal shine on the way from manufacture to your garage. But you will get corrosion immediately after you put your plane outside your garage.

IMG_7974 by Dozer, on Flickr
IMG_7975 by Dozer, on Flickr
IMG_7978 by Dozer, on Flickr
IMG_7977 by Dozer, on Flickr

[BillL]

How close are you to salt water?

[Dozer]

4 miles. It's far enough

[David Paule]

Location, location, location.

My '55 C180 had no corrosion until, in '91, it spent 6 months tied down outside of Philadelphia. That's still the only corrosion it has. The rest of its life was spent in the dry midwest except for 3 years in a tight hangar in Oxnard, CA, that didn't add any new corrosion. I've had it since '86 and know it pretty well.

Dave

[fl-mike]

Considering that I can SEE the beach from my hangar....yes.
Shade hangars here are the worst. The salt spray settles on the plane, and the dew keeps it working. Better to leave it outside so the sun can dry it and the rain gives it a wash.

[Desert Rat]

Originally Posted by Dozer

4 miles. It's far enough

evidently not

[Vlad]

The last two pictures seems to be a filiform type of corrosion under the protective layer of plastic. I had similar when I started building 16 years ago. Over a decade I keep my unpainted RV outside and didn't notice severe corrosion. There are spots like yours on access panels but nothing major.

[riseric]

Were the panels still covered with the "protective" vinyl?
I had filiform corrosition on parts of the empennage (still with the vinyl) when stored in a basement garage (read high humidity) in the middle of Europe, far from any ocean and salty air. Removed the vinyl, and never saw corrosion since.

[BillL]

Here is a study that says 50 miles. That pretty much covers Naples, FL.

4 miles is pretty close. Whitecaps and breeze keeps the aerosols going. 2023 alloy needs the best protection, 6061 is pretty immune according to DOD studies.

Now (waiting) for the chromate discussion.

[lr172]

Originally Posted by Vlad

The last two pictures seems to be a filiform type of corrosion under the protective layer of plastic. I had similar when I started building 16 years ago. Over a decade I keep my unpainted RV outside and didn't notice severe corrosion. There are spots like yours on access panels but nothing major.

+1

That looks exactly like the corrosion that appears regardless of salt when the plastic covering is left on. You can even see the outline of exactly where the plastic lifted off the metal due to the curvature, leaving that perfect little pocket to hold moist air and slow evaporation.

Larry