How To Polish Paint: Part I

In a perfect world, you wouldn't need to polish your car's paint. Cleaning and waxing is all that's really necessary to protect and beautify your car's finish. Unfortunately, we don't live in a perfect world. Your car's paint is bombarded by contaminants and assaulted by foreign objects every day. This is the forst part in my guide to polishing paint. This part will discuss different grades of polish, and what you can and cannot fix by polishing.

Some automotive appearance experts suggest that it's possible to maintain a car's paint without polishing at all. I'm not as optimistic. I recommend polishing when it's necessary to solve a specific problem or to achieve a desired result.

This article discusses the many different kinds of car polishes and their purpose.
UNDERSTANDING CAR POLISH
Before we can talk about polishing, we need to establish a common understanding of what polish is. The word polish is highly misused throughout the car care and appearance industry. For our purposes, a paint polish is an abrasive lotion or cream used to remove small amounts of the paint's surface. The cutting ability of the polish will determine the amount of paint removed with each hand stroke or each revolution of a buffer, as well as the resulting finish. A fine polish will create a bright, glassy finish, whereas a coarse polish may cloud the paint's surface. Each polish is designed for a specific purpose (e.g., repair or refine) and application (e.g., hand or machine).

Here's how I classify polishes:

Abrasive paper or pad - An ultra-fine grade of sandpaper (1200 to 3000 grit) can be used effectively to level a paint finish and remove imperfections. I mention sandpaper here because it is an abrasive, like all polishes, and it has its place in the polishing chain.

Compound - A compound, often called a rubbing compound, is a cutting polish designed to remove heavy oxidation, some common forms of paint damage and defects, and the scratches created by fine sandpaper.

Polish - A specially formulated blend of components designed to remove minor scratches, surface imperfections, water spots, acid rain spots, light oxidation, and the swirl marks created by compounding with a machine.

Glaze - A very fine polish. Some glazes are safe to use on fresh paint, as they do not seal. A glaze does not have enough cutting power to remove imperfections, but will increase surface gloss.

Pre-wax cleaner - A polish containing chemical cleaners to help remove minor surface contamination and dirt not handled by normal washing or claying. You may be asking why I didn't mention detailing clay. While detailing clay is an abrasive suspended in a clay or elastic base, its purpose is to remove particles from the paint's surface and not the paint itself.
Car Polish Selection

The car care market is flooded with polishes, each promising to work one miracle or another. Selection is difficult at best. For the purpose of our discussion, it's necessary to create a reference. It's important to note that polishes may be specifically created for hand or machine use. The difference between a machine polish and a hand polish is how the abrasive material breaks down in use.

The abrasives in most polishes break down (diminish) into finer particles, allowing the polish to "buff out." If you use a machine polish by hand, the particles may not break down, and the finish will not buff out properly. Conversely, using a hand polish with a machine will cause the polish to break down too quickly, and you won't get enough cutting action. A few polishes work by hand or machine, because they don't use diminishing abrasives or they are not temperature sensitive (buffing pads create heat).

Reasons to Polish Your Car's Paint

Many people believe that cars come off the assembly line with perfect paint. That's far from the case. There are many conditions that cause minor paint flaws requiring additional finishing work. Dust nibs (small particles that land in the paint while it is still wet) are a good example. Most car manufacturers take care of these problems at the factory using abrasive finishing materials. Sometimes it is the car dealer who recognizes the flaw and fixes it.

Repairing minor paint flaws through polishing is not harmful to the paint system unless you remove too much paint. If more than 50% of the clearcoat finish is removed, you stand a good chance of premature paint system failure. If more than 75% of the clearcoat finish is removed, you will experience immediate paint system failure. It can be a very fine dance between success and failure. Here's a general rule to follow. If a scratch or other flaw can be felt with your fingernail, it's too deep to be completely removed through polishing. That's not to say that polishing won't help hide the flaw; it will.

If scratches run deep into the clear coat, as illustrated in our next 3M diagram, polishing cannot fix the problem. However, polishing a deep scratch will hide or lessen the appearance of the problem.

Non-clearcoat finishes have the same basic rules. You should not remove more than 50% of the top coat (color coat) finish when repairing a scratch or other paint flaws. It is important to understand how a polish can be used to "hide" scratches and other micro marring. Scratches have hard edges that run at a 30 to 60 degree downward slope. It is the hard edge and angle of a scratch that creates a perfect opportunity for light reflection. It is this reflection that enhances the visibility of the scratch. A good polish rounds the edges of scratches, reducing reflection. Here is a list of problems that can be fixed or improved through abrasive polishing:

* Scratches - Surface abrasions that do not extend past the first 25% of top coat material can be fully repaired by polishing. Deeper scratches can be improved as long as they do not fully penetrate the color coat into the primer.
* Scuffs and rub marks - Scuffs are broad, shallow surface abrasions that are easily repaired by polishing. Rub marks are commonly caused by shoe heels (getting in and out of the car) or the bumpers of other cars. The rub mark is generally a transfer of rubber or other vinyl material to the paint surface. Rub marks are easily removed by compounding and polishing.
* Micro marring - Micro marring, also known as swirl marks and spider webbing, means very small scratches in the paint's surface. Micro marring is created by machine compounding and in everyday use and maintenance of the vehicle. Micro marring is easily removed by compounding and polishing.
* Etching - Paint etching is a common problem caused by hard water (tap water) or acidic water (acid rain). Bird droppings are another common cause of paint etching. Depending on the severity of the etching, polishing will repair or lessen the appearance of etched spots.
* Dust nibs - Small particles of dust and other foreign material that land on the paint during the painting process create small nibs on the surface. Wet sanding, compounding and polishing will remove the visible portion of the nib and level the paint.
* Orange peel - When a car is painted, the paint is applied at a consistency and thickness that allows the paint to flow (briefly) and level. If the paint is applied too heavily, sags and runs will result. If applied too thinly, the paint does not properly flow and level, causing an uneven surface called orange peel. If the orange peel is not severe, abrasives can be used to level and glaze the finish to match the rest of the vehicle.
* Runs and sags - If paint is applied too heavily, sags and runs will result. If the sag or run is in the clear coat, it can be repaired, but not if it is in the color coat or primer. On a non-clearcoat paint, sags and runs in the color coat can be repaired.