sanded through the alclad--corrosion issue?

RV10Rob · #1 09-09-2007, 11:33 PM

Hi, all.... I've sanded out some scratches in a skin with the maroon scotchbrite pads. For the interior sides, I'm using a self-etching primer, so I figure there's no issue since I'm planning on priming soon.

What about the exterior? I've exposed the aluminum underneath the alclad--should I be worried about corrosion? I'm going to paint it eventually, but not for a couple years at least. I don't want to use the primer on the outside now, since I hear it makes paint adhesion more difficult later. Any suggestions? Unless I hear a better idea, I'm just going to leave any new scratches as-is on the exterior, then sand them down when I get closer to painting.

Thanks...

-Rob

szicree · #2 09-09-2007, 11:44 PM

Are you really sure that you're through the alclad? You'd have to scrub a loooong time by hand with scotchbrite to get through it. I actually tried it once while checking with a micrometer every so often. It took a whole lot o' scrubbing.

Camillo · #3 09-10-2007, 02:00 AM

When I re-primed my first empennage ribs, I had to scratch a lot - even with sandpaper - to take all old prime off. And you can easily see the slightly different colour (this was my idea...) detween the pure aluminium and the the alloy.

Anyway, you can now prime and de-prime (and re-prime) with acetone before painting or I think you can apply oil, as Van's does with QBs.

Only my humble opinion...

TSwezey · #4 09-10-2007, 05:05 AM

Go buy some alodine and rub into the areas that you have sanded. This will protect it for many years.

RV10Rob · #5 09-12-2007, 09:52 AM

Thanks, all... on second thought, I may not have sanded through the alclad. I'll check it out again, but it sounds like I might be okay as-is.

Phil · #6 09-12-2007, 11:42 AM

I've got some alodine that I keep on hand. If I believe I've gone through, I go ahead and spray some on. It makes the part ugly to look at, but once the primer goes on it doesn't matter.

Phil

cytoxin · #7 09-12-2007, 02:38 PM

is only .002 thick and is buttery soft..comes off redily esp with a RED pad.
just alodine it for now.or sem or any other self etch. good luck.

FlyerJumper · #8 09-12-2007, 04:10 PM

Regarding touchups with alodine, these are nice to have...

Touch-n-Prep Pen

Look around, you can find them cheaper (I think I gave a little over $50 for ours from a local supplier).

szicree · #9 09-12-2007, 04:23 PM

Quote:

Originally Posted by cytoxin

is only .002 thick and is buttery soft..comes off redily esp with a RED pad.
just alodine it for now.or sem or any other self etch. good luck.

Ok, not that it matters, but have you ever actually checked on this? I had seen this statement made over and over on here and other sites until I finally tested it myself. I found that red scotchbrite (by hand) takes a real long time of continuous, vigorous scrubbing. I think a lot of folks are under the false impression that the alclad is gone when the shine is gone.

TSwezey · #10 09-12-2007, 04:32 PM

I sand it with 220 grit paper with an orgital sander before I put on the alodine.