Polishing (also referred to as buffing and/or compounding) is the step in the detailing process that yields the most dramatic difference in your paint's appearance. The objective of polishing is to remove imperfections in the clear coat that cause the paint to look dull. Surface imperfections can include swirls, scratches, water marks etc. Over time these surface imperfections accumulate causing light to fragment instead of passing directly through the clear coat yielding less gloss and depth. When these imperfections are removed, you will reveal the true potential of your vehicle's paint.
The most common type of paint damage are swirl marks. A swirl mark is a very thin and shallow scratch on the surface of your paint, that often comes from washing and drying improperly. Although some waxes on the market claim to "remove" swirl marks the reality is they just fill in the scratches hiding them temporarily. To eliminate these imperfections permanently requires polishing the paint surface.
Why Use a Buffer?
Theoretically you could take the softest pad with the least aggressive polish and eventually repair even the heaviest of paint damage. Reality is the time this would take makes hand polishing not a very feasible method other than for very light damage or "spot repair" To put this in perspective imagine that an average polisher can operate at say 6,800 oscillations per minute. Imagine trying to move your arm 6,800 times per minute for hours on end, all while exerting pressure on the applicator pad. Not only does polishing by machine dramatically decrease the time required to complete the job, you will get better results with a machine as well. Using a machine polisher will work in the polishing particles more thoroughly and evenly than you can by hand, achieving better results. However, the results you achieve (and how it takes to achieve them) is also greatly affected by the selection of buffing pad(s) and/or polish/compound(s). Both pads and polishes are available in a variety of aggressiveness levels which have a great bearing on how quickly paint is repaired.
One of most common fears that most novices or "weekend warriors" have that makes them reluctant to polish their own vehicle is that they will damage or "burn through" the paint. Reality is that Random Orbital or D/A type polishers are extremely safe to use particularly when mated with the right pad/product combo. An expert professional polisher working with a "time is money" mentality may use a rotary type polisher with a very aggressive pad/compound combination to repair paint damage as quickly as possible. The DIYer rarely needs to complete their project that quickly and are more concerned about the final results as opposed to how quickly the results are achieved. By simply using a Random Orbital type polisher with a less aggressive pad/product combination than a pro would use a novice can very safely achieve stunning results in just a bit more time and have fun doing it!