bodwork / paint on aluminum body?

[Arrowhead]

I have a friend that is a metal shaper that built an aluminum replica from scratch. The body is aluminum and he was asking me about painting it but is concerned about any filler work (although minor) telegraphing do to the high expansion rate of the aluminum panels. Obviously the aluminum is thin and expands quite a bit when exposed to the heat of the sun so he does have a valid concern. Any other issues with painting the aluminum or treat it like regular steel? DA with a 80 grit / clean / 2 coats of epoxy? I'm thinking maybe a finer grit like 120 might be better as the metal is so soft.

 

[Barry]

Same issues with a vette, you want the minor filler or glaze work over epoxy.
Also another very important note sanding deeds to be done day of epoxy, not day or week before.80 or 180 on a day is fine, 80 causes no problems except for rivets.

 

[flynams]

you will need to wipe down 4 or five times before the epoxy and make sure your rag has no black on it

 

[Bob Hollinshead]

I've never seen any telegraphing of filler on aluminum, epoxy primer first is a must IMO, I would think the expansion rate differences of aluminm/filler vs. steel/filler favor aluminum. But my aluminum experiences are mostly limited to oem automotive panels not custom fabrications.

 

[Arrowhead]

Thanks for the replys. I think I'll take some scrap and beats some dents in it, sand, epoxy, fill, block, paint, clear and leave out for the rest of the summer and see what happens. He's in no hurry. That will also give him some reassurance.

Same issues with a vette, you want the minor filler or glaze work over epoxy.
Also another very important note sanding deeds to be done day of epoxy, not day or week before.80 or 180 on a day is fine, 80 causes no problems except for rivets.

Great tip Barry, that aluminum will oxidize quick so I can see how getting it coated right away is so important.

 

[Brad J.]

I did a 24' Marmon that had an aluminum body that never telegraphed. Not an extensive amount of filler but it was almost 90 years old so it had some.

I used waterborne and like Flynams I washed everything until the rag was spotless.

I believe a new body in aluminum would be a lot easier to handle than an old one. Steel rods wrapped with aluminum for the fenders causes a mess around the edges.

 

[shine]

this is one of the few times i will recommend metal prep . aluminum is way less forgiving than steel . use a quality prep solution right before you shoot it .