It may seem unlikely that the first step in polishing aluminum to a near-mirror shine is to score an extra crusty set of '70s vintage US Indy slot mags of off an equally '70s vintage Toyota SR5 Liftback at the local junkyard. Mag wheels are named as such because the aluminum is mixed up with a bit of magnesium to form a stronger alloy. Over time and with exposure this alloy tends to turn a dull grey. Even the crustiest of aluminum wheels can be brought back to a mirror shine with a fair amount of elbow grease and careful use of cheap power tools.
Buffing out aluminum to a mirror shine involves smoothing out the irregular surfaces of the metal itself on a level unseen to the naked eye. Under an atomic-powered electron microscope, the surface of a dull or pitted aluminum wheel would look sort of like a bowl of 99-cent store corn flakes - full of jagged peaks and valleys. When light hits rough surfaces it diffuses and dissipates. We see dull. A polished aluminum surface under a microscope looks more like a bowl of hot Cream-o-Wheat - slightly bumpy, but mostly smooth and flat. When light hits a mostly flat reflective surface it has nowhere to go but right back at you. The jagged peaks get knocked down by buffing.
Don't Let the Smooth Taste Fool You
The best way to smooth out a bowl of cornflakes is to eat it. Smoothing the peaks and valleys of aluminum requires use of a series of buffing wheels and polishing compounds. The buffing wheel works with the embedded abrasive buffing compounds to smooth out the aluminum. Steps and stages are key. Each wheel and compound must be used in sequence. Stiff buffing wheels with coarser compounds work into softer buffing wheels and less aggressive compounds to produce the shine. The right balance of buffing wheel revolution and pressure is brings it all together. Too little pressure and compound along with bits buffing wheel will end up all over the garage. Too much pressure and the compound can dig in and burn the surface instead of buffing it. Practicing on the back of the wheel before going nuts on the front is a good idea. Work from coarse to smooth. Use a dedicated buffing wheel for each compound.
While standalone buffing machines are very handy and not really all that pricey, we didn't have one. We weren't out to win any Funkmaster Flex car show trophies anyway, so we used a 29-buck handheld buffer and a few 6" buffing wheels. We were shooting for a shining set of daily drivers on the cheap. As with using any type of power tools caution must be taken. At best bits of the buffing wheel, compound, and microscopic aluminum dust will get everywhere. At worst, high RPM high torque power tools can be dangerous! Wear a mask, gloves, and safety goggles at all times while buffing aluminum. Make sure the wheels are bare aluminum before beginning. Any paint or clearcoat on the wheels will be quickly destroyed by the buffing process.
Stuff You'll Need:
· Crusty Set of Mag Wheels
· Degreaser, Bucket, and Scrubbing Stuff
· Utility Knife and Hand Tools
· Hose and Nozzle
· Power Buffer of Some Kind
· Buffing Wheels and Arbor
· At Least Three Degrees Buffing Compound (Coarse, Medium, Fine)
· Clean Rags
· Safety Goggles, Gloves, and a Mask
Remove anything that will get in the way of buffing. Valve stems. Wheel weights. And so on. Make like Mr. Clean with the degreaser and remove all dirt and crud. Grab the hose and rinse the wheels. Buffing crud into the aluminum with power tools is a bad idea. Don't run the wheels through the dishwasher. People get mad.
Deposit the wheel onto a five-gallon bucket. The local donut shop is a good source for five-gallon buckets. Some even smell apple-filling fresh. Use a flat file to smooth out any nasty curb rash. Don't go crazy removing material. Just knock it down mostly flat so it the buffing wheels don't get caught on jagged aluminum and disintegrate.
Buffing compounds are made in abrasive degrees with wheels to match. Coarse. Medium. Fine. Start with a bit of the coarsest or most abrasive compound on the stiffest buffing wheel.
Use the right combination of revolution and pressure to get the compound working. Let the buffing wheel material and compound do the work. Buff one section at a time, overlapping slightly until the whole wheels is done.
Clean the entire wheel surface of buffing compound in between each step. If the balance is right there won't be much to clean off.
Use a separate wheel for each compound to stop contamination between steps. Here a less abrasive compound is used with a loose sewn wheel for a finish buff.
Use a hand-applied liquid polish for the last and final step. Clean all the buffing compound and cloth off the safety goggles and buff out the other three wheels.
And You Will Know Us by the Trail of Parts [Internal]