don't prime inside of skins?

[Jake14]

The instructions from the paint manufacturer (Stewart Systems) say that the recommended etching and then scuffing will remove the cladding form alclad.

I can understand priming the interior parts since even the alclad ones get buffed, deburred and scuffed, so a lot of the aluminum cladding is gone anyway.

But why get rid of the cladding on the inside of the skins only to replace it with another (better or worse?) protective layer?

First-time builder...Just wondering....

[az_gila]

The Alcad layer on a 0.025 skin is 0.0012 inch thick per side.

If you are removing that much during a maroon scotchbrite wipe and etch you are rubbing too much and/or letting it sit in the acid for too long.

[scrollF4]

It removes some alclad, but only a small bit if you don't get too crazy with the etching. It doesn't remove it all, so you're making it better.

[Jake14]

from the manufacturer's instructions:

"Etching removes the top protective layer of pure aluminum from the surface which makes the aluminum more susceptible to corrosion"

Makes it sound as though the entire cladding layer is removed....

[RVDan]

Yeah, the top layer, but not .0012 worth of Alclad unless you etch far too long.

[az_gila]

Originally Posted by RVDan

Yeah, the top layer, but not .0012 worth of Alclad unless you etch far too long.

Yes... this paper talks about less than 1 gram per sq. ft. removed to get a matt finish.

http://aluminumsurface.blogspot.com/...hot-topic.html

If my calculations are correct that is about 0.00016 inches thick.