[dnimigon]

I've been rubbing and rubbing as I build my RV-9 and when it came to the wing skins I thought their has to be a better way. well I'm a contractor by trade and decided to try a small vibrating sander(the kind you all probably have kicking around) but instead of the sanding paper I just set a peice, say 4 X 4 of scothbrite down on the skin, set the sander which usually has a rubber pad on the bottom down on the scotchbrite and turn it on. The rubber base of the pad keeps the scotchbrite held firm and it doesn't take much pressure to buff. As far as dimpled areas it roughs them up nicely. Then I wipe off the excess. Then clean using your favourite cleaner. As far as I'm concerned this works excellent and with much less effort. I'm using it now on all my flat surfaces.

 

[N941WR]

Why are you scotchbriting the entire skin? Are you getting ready to prim them right after you scuff off the alclad? I must be missing something here.

 

[vfrazier]

Just scuffing with Scotchbrite isn't enough to break through the Alclad. You'll need something more aggressive to do that.

You can tell when you're through the Alclad because the base metal is much harder and has a slightly different appearance and feel. At least, that has been my experience on various corrosion and scratch repairs over the years.

I painted my Rocket back in 2003 using PPG basecoat/clearcoat. The first step was to scuff everything with Scotchbrite exactly as described above (sorry, there's nothing new under the sun!). I skipped the alodining because of the health hazards of that stuff (where do you think it goes after you rinse it off in your driveway!?) and have had zero adhesion or other problems. In fact, the paint looks like day one even after 7 years. Good stuff if you follow the directions.

YMMV

 

[dnimigon]

I'm only priming the interior surfaces, prior to assembly. I find the black scotchbrite pads are more aggessive. After that I use an my hand to give it a good once over, then a alodine cleaner which is rinsed off. When dry I follow with wiping the sheet or part down with a good auto metal cleaner used in body shops. This gives me a clean, dry, ready to prime surface. Never had any issues yet. In fact it's hard to scratch it once good and dry. Very good bonding i assume.

 

[N941WR]

... I skipped the alodining because of the health hazards of that stuff (where do you think it goes after you rinse it off in your driveway!?) ...
YMMV

Vince,

I worked with a guy who suggested I buy some citric acid to prep the aluminum for painting. I never tried it but have always wondered how well that would work.

 

[Fedico94]

PreKote fan

Started my RV9A project 4 years ago and used scotchbrite pad and the prekote with Randolph epoxy primer and AKZO epoxy primer. Impressed with adhesion and flexability without cracking or seperating from Al sheet.
Last week I wnated to remove some overspray from the fuselage and I used a silicone spray material from a can (sold to lubricate metal parts) I noticed that it cleaned off the overspray and brightened the alclad plate. Anybody have similar experience ? About 1/2 the plane will be bare Alclad no paint.

 

[Master Designs]

....suggested I buy some citric acid to prep the aluminum for painting...

That is basically what is used to clean parts before powdercoating. It is just a basic cleaner and degreaser, safe and cheap. I don't know if I would use it on an entire aircraft.... I think better solutions are out there to put a tooth on the aluminum instead of just degreasing it.

 

[Av8torTom]

Careful!!!

Started my RV9A project 4 years ago and used scotchbrite pad and the prekote with Randolph epoxy primer and AKZO epoxy primer. Impressed with adhesion and flexability without cracking or seperating from Al sheet.
Last week I wnated to remove some overspray from the fuselage and I used a silicone spray material from a can (sold to lubricate metal parts) I noticed that it cleaned off the overspray and brightened the alclad plate. Anybody have similar experience ? About 1/2 the plane will be bare Alclad no paint.

That silicone may get you in trouble if and when you decide to paint. Very hard to get off and will prevent paint from adhering.