Body car repair :
the art of metal buffing

The final stage of a body car repair : getting ready to buff

Once the surface is smooth enough to buff (i.e. 220 grit or finer for soft metals like aluminum, brass, copper, and pewter. 400 grit or finer for steel, and stainless) the buffing process can begin. Trizact Bands can be used to substantially speed up the buffing process. When using the A-30 (700 grit) and A-16 (12000 grit) bands on aluminum or other soft metals, use either compound or grinder's grease on the Trizact band. Running these fine belts dry during the buffing process of your body car repair job can pull grains of metal from the part and drag them across the surface resulting in a rough finish. Using the Trizact bands saves substantial time and eliminates one or 2 buffing steps.

Buffing Safely

Safety is always important in any body car repair work. Buffers spin at a high RPM (usually 3600 rpm), which is more than enough to launch parts across the room or into you if the part is not held properly. Make contact with the lower (4:00 position when viewed from the left) portion of the wheel. The wheel should pass over corners and edges, not toward corners and edges. Hold the piece tightly and apply light (about 2-lb.) pressure against the wheel. Do not insert your hand or fingers into openings. Practice how you will hold the piece against the wheel before starting the motor. Once you're satisfied you can hold the part safely you're ready to put on your gloves, dust mask and eye protection and begin buffing.

To apply the compound to the wheel, tear down the cardboard tube and hold the exposed compound against the wheel for about 2 seconds. You'll see how the wheel takes on the color of the compound. You'll also notice how the wheel turns black almost immediately when you start to buff. This black build-up is not harmful to the wheel or the part being buffed. Rake the wheel if you notice excessive metallic build-up or at the start of the body car repair work to prevent scratching the surface.

As you progress into you body car repair job, from one compound to the next finer grit remember to clean any residue with PRE Painting Prep, Metal Wash, or hot water and detergent and change the angle by 90 degrees (or as close to 90 as the configuration of the part allows). Before you stop to inspect your buffing work, take a few passes with the direction of rotation. This technique will help remove fine scratches for a better shine. In the finishing industry a "black finish" represents the highest reflectivity. If the buffed surface can reflect black without showing any fine scratches, then the best finish has been achieved.

Preserving The Shine is a critical aspect of the body car repair

Buffed surfaces will stay oxide free longer than rough metal, but in many cases the durability of the shine can be enhanced with the use of clear coats. Stainless steel, gold, and platinum do not need to be top coated with a clear but brass, copper, aluminum, silver, pewter and most other metals will benefit from a clear coat. The most durable clear to use is a Super Gloss Clear HotCoat powder. Some types of brass, bronze and steel can significantly oxidize when exposed to the curing temperature, in which case a Diamond Clear Gloss for Bare Metal (Aerosol or pint form) can be easily applied after degreasing for durable oxidation prevention during the body car repair process.

Which Buffing Motor is Right for You ?

When selecting a buffing motor a number of factors need to be considered. If you body car repair job is predominantly for buffing metal choose 3600 RPM and if you'll be predominantly buffing plastic, 1800 RPM is preferred. More powerful motors yield faster results because larger diameter wheels and/or multiple wheels can be used on the same shaft. The lower power motors will get the job done but take more time. For buffing light pieces of stainless steel trim many prefer a smaller buffing wheel, which can be used on the small buffing motors or modified by making a small cut north, south, east and west around the arbor hole to fit the larger buff motors.

The Baldor Motors have long been the industry standard for excellence and offer slightly longer shafts for improved maneuverability.

Mandrels and Adapters - Using an Existing Motor For Buffing

If you prefer to use an existing motor for polishing and buffing operations during the body car repair work, a wide variety of Motor Adapters to fit motor shafts from 3/8" to ¾" are vailable in the market. The 1/2" and larger mandrels are available in right and left-hand thread. To determine which thread you need, examine the unit to see if the shaft is to the right or the left of the motor. If your shaft is to the right, use a RH adapter, and a LH adapter if the shaft is to the left of the motor. A Wheel Arbor is used to mount smaller wheels with ½" mounting holes to your drill or die grinder. If using this adapter with a drill, be sure the drill spins at least 2500rpm or more. Low rpm is the leading cause for difficulty in transferring compound to the wheel. For Mini Buffs (1-2" diameter) use 2 mandrels - 1/4" and 1/8" shank. These two sizes allow the buffs to be used with most die grinders.