Painting aluminium

[Incorrigible]

Just need advise on a cheap primer, I don't really want to go down the expensive etching stuff route unless I can't avoid it

It's for a race car but still needs to look OK (a couple of coats polished, not 17 coats flatted, polished, hand glazed, and carnuba waxed), top coat will be a flat colour, probably standard 2 pack

Cheers

Ben

[apguy]

Unfortunately on bare aluminium (or any other metal) you will need an etch primer. Otherwise you will not get the adhesion to the base metal.
After that you can use the cheapest primer you like!

[Incorrigible]

Yes, but on steel you can get away with the cheapest of cheap celulose red oxide

Can you do that on ally, never tried it

[Pigeon]

No, aluminium's not so easy like that. (Zinc (galvanising) is even worse.)

I would think the best paint for ally might be an epoxy-based paint, because as long as you are scrupulous about cleaning the surface (abrasives followed by acetone) it will chemically bond to the ally.

[Incorrigible]

Thanks Pigeon

Cheap was really what I was after, as I can forsee a few re-painting incidents

Did you mean just bung an expoxy top coat straight on the ally or what (that would be fine for the level of finish I need)

[Pigeon]

Yes, if one coat will give you a good enough finish, that's what I would do. The important bit is the abrasive cleaning followed by degreasing with acetone (from glass fibre materials suppliers), so that the chemical bonding works.

[wolf1]

I've painted my Landrover before without any etch primer and never had any problems with the paint. I'd like to add that most of the panels were bare aluminium prior to being primed using spray putty (thicker than normal primer to cover all sorts of bodges!) Kept her for five years before selling and not an iota of peel etc.

[Incorrigible]

Wolf, do you mean a standard high solids primer ??

and Pigeon, acetone ?? do you know if a standard panel cleanser/de-greaser will do the trick

Antone else ??

[Fatboy]

Acetone's probably the best solvent for the job - it'l dissolve almost any grease/oil you can think of, and dries off quickly.

It's also pretty cheap, if you buy it in large bottles/drums from a glass fibre supplier.

[Pigeon]

On occasions I've tried to make do with something other than acetone for cleaning aluminium before epoxying it, it never works as well. Same with other things that require really thorough degreasing. As Fatboy says, you can buy it in large quantities at a reasonable price from glass fibre suppliers, in which world it plays the same role as brush cleaner in painting.

[wolf1]

Incorrigible said:

Wolf, do you mean a standard high solids primer ?? and Pigeon, acetone ?? do you know if a standard panel cleanser/de-greaser will do the trick Antone else ??

Nah it's actually called spray putty(mustard coloured high build primer). Acts as a good barrier coat as well. To clean panels before laying any paint I wiped it all over using standard thinners and then a tack cloth. You can complicate it all you want, at the end of the day you are painting a race car not a concours show car. It all depends on how much money you want to waste.

>> Edited by wolf1 on Sunday 19th September 02:55