1) You can blast it with plastic media (walnut shells might also be OK).
This approach is commonly used to strip paint from thin aluminum
aircraft fuselages, but on very thin metal it must be done carefully to
avoid stretching the metal, which can create an "oil can" effect.
However, this should not be a problem with thick aluminum wheels.
Note: Most aluminum wheels, in my experience, are made of either 6061 or
2024 aluminum. These are tough alloys commonly used in aircraft
components, and contain a certain amount of copper and magnesium. In
addition, a thin coating of pure aluminum is often applied to the
surface of these alloys to help control corrosion. If there is such a
thin aluminum coating, you certainly don't want to disturb it by using
an abrasive blasting media that is harder than aluminum.
2) You can use a chemical stripper that is safe for aluminum.
There are several chemical strippers routinely used by aircraft
refinishers that do not react with aluminum. These are quite toxic and
messy to use. Check with an aircraft operation to find out what they
use.
There are also some "safety strippers" that MIGHT work OK, but I'd make
SURE that they don't react with aluminum before attempting to use one.
As far as I'm concerned, these are quite suspect.
For refinishing, some sort of surface preparation is recommended to make
the primer bond better. DuPont makes a one-part "Alumiprep" solution
that etches the surface to prepare it for painting. Or, you can use
DuPont's two-part "Etch and Alodine" set that both etches and creates a
tough chromate conversion coating that helps resist filiform corrosion
under the paint. These prep solutions are easy and "relatively" safe to
use, since they don't have to be sprayed...just apply directly to clean
metal and rinse. If the surface is prepared in this way, a self-etching
primer is unnecessary, although it's still not a bad idea. Use a good
compatible primer-sealer and quality top coat.
Regards,
Alan
(Salt Lake City, Utah)
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