WHAT IS POLISHING?
To simplify, polishing a car simply means that a polish is applied to the paint with a machine buffer in order to remove a certain percentage of the paint's defects. Polishing is the process of removing a certain level of the clear coat in order to improve or fix completely, minor scratches and defects. When your car is polished, it is important to understand that at a root level, some of the clear coat is coming off. Now when compared to something like wet sanding ; polishing removes a very minor amount of the clear coat, but this is the reason that polishing is not something that needs to be done on a regular basis. There is only so much clear coat on a car.
Polishing is not used to repair deep scratches or serious paint defects, that must be fixed through a process called wet sanding, however light to medium scratches can be dramatically improved and fixed through polishing.
WHY POLISH A CAR?
As cars are constantly being barraged and damage through road use, our vehicles encounter scratches, chips, and all kinds of defects in the paint. Even washing a car is potentially dangerous if not done correctly, as wash scratch or swirls marks may appear. Most of these defects (scratches, swirls, etc...) exist in the paints clear coat. Some will be deeper and some will be more surfaced, so polishing essentially removes these defects, and restores the car paint to its "like-new" or "showroom" condition.
ONE STEP VS TWO STEP POLISH
There are different degrees of aggressiveness in different types of polish. If a car needs nothing more than a one-step polish, that means that one round of polish will be applied to the whole car. This is reserved for car paint that is not heavily damaged and does not have many defects. A one-step polish will be on the less aggressive side because a heavy cutting polish is not necessary to remove minor scratches.
A two-step polish is exactly what it sounds like. A car that has heavier scratching and swirling will need something more than a simple one-step polish. First, the car is polished completely with a heavy cutting, aggressive polish, then a final round of a less aggressive polish is applied to fix any final minor scratches, and bring out the maximum showroom car shine. Some situations may even call for a multi-step polish.
Swirl marks are one of the main issues (if not the main issue) that require a person to polish a car. Swirl marks can come from a variety of different sources, washing a car (called wash scratch), touching or leaning on the car, or just simply driving the car!
Though swirl marks look as if there are circular, they are not. Swirl marks are nothing more than thousands of random little scratches, going in every direction, but when the sun shines on the paint, they appear circular because of the sun's shape. You'll notice that they can only actually be seen in the sun, if your car is parked in the shade it will look like they are not there.
For the most part, swirl marks can be removed through polishing. Swirl mark scratching tends to be more surfaced than specifically isolated scratches. Below is an example of a car that had some swirl mark damage:
Sometimes what appears to be a scratch is actually something called car transfer. Car transfer is paint or residue that has transferred from whatever the car brushed up against. For example, if a car brushes up against the white garage door, more than likely there will be what looks to be a white scratch but in turn, it is nothing more than the paint from the garage on the car. Transfer can be difficult to remove if one does not have the right products. Transfer also has the ability to hide scratches, in other words, there may be a lot of scratching that cannot be seen until the transfer is removed. We always take necessary steps to remove transfer before polishing or wet sanding a specific area because it is not always clear if something is a scratch or if it is transferred.