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While plunging headlong into things is sometimes required, most of the time it
is better to take on challenges one step at a time. This is often the case in
the mechanical world of automobiles. Examples abound. Tightening the lug nuts
on a wheel. Using the proper sequence of torque while cinching down a cylinder
head onto an engine block. Even something as mundane as getting a car or truck
paint job to shine on a Sunday afternoon requires careful steps. Rinse. Wash.
Dry. Wax. Buff. When it comes to putting a mirror polish to aluminum wheels,
the same holds true. Each step of the process brings the aluminum closer to a
proud shine.
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The number of steps required to bring an aluminum wheel to a mirror finish
depends largely on the condition of the wheel itself. A good rinse and dry may
be the one and only step if the wheels are in excellent shape. That same rinse
may be the first of many steps if neglect has left the once shining wheels
looking grey and cloudy. With a fair amount of elbow grease and careful use of
power tools, even the crustiest of junkyard-sourced aluminum wheels can be
brought back to a mirror shine. To put this to the test, we went and got an
extra crusty set of '70's vintage US Indy slot mags off of an equally vintage
Toyota SR5 Liftback at the local self-service junkyard. They are called Mags
because aluminum is mixed up with a bit of magnesium to form a stronger alloy.
This alloy is what requires polishing. The first step in this case amounted to
a long day at the junkyard fussing with stubborn lug nuts.
Stepping Stones
Buffing out aluminum, or any metal for that matter, involves smoothing out the
irregular surfaces of the metal itself. While an aluminum wheel may feel
smooth, the surface is actually quite rough when it comes to reflecting light.
Under a microscope, a dull or pitted aluminum wheel would look sort of like a
bowl of corn flakes. Jagged. Edgy. Rough. When light hits these rough
surfaces, it diffuses and dissipates. The wheel appears dull because the light
stops at the surface. A polished aluminum surface under a microscope looks
more like a bowl of hot oatmeal—a little bumpy, but mostly smooth and flat.
When light hits a mostly flat surface it has nowhere to go but right back,
hence the shine.
The best way to smooth out the peaks and valleys of aluminum is to use a
series of buffing wheels and compounds. The spinning material of the buffing
wheel works in conjunction with the abrasive material in the buffing compounds
to smooth out the aluminum. The steps are key. Each buffing wheel and compound
must be used correctly and in sequence. Stiff buffing wheels with coarser
compounds work into softer wheels and compounds with less of a bite. As
important as the wheels and compounds is the buffing technique. The right
balance of rpm and pressure is the trick. Too little pressure and all you get
is compound and bits of the buffing wheel all over the place. Too much
pressure and the compound can burn the surface instead of buffing it. Practice
on the back of the wheel to get a feel for the process before going nuts on
the front. Always work from coarse to smooth, and use a dedicated buffing
wheel for each compound.
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