Detailing - May 2009

Polish: What's in Yours? Part II
By Kevin Farrell

The abrasives look like powder on the panel. Directly to the right of the powder is where I rubbed it into the paint surface a little bit to get a feel of how aggressive they can be. The top abrasive leaves more hazing behind than the bottom abrasive does, so the top abrasive is more aggressive and will cut more, but will also mar and haze the finish more.
A perfectly polished panel in shop lighting with no flaws visible to the naked eye.
A special light shone on the panel accentuates any imperfections that may still be present even after polishing. The areas where the light is shining directly on the paint surface shows some slight marring left behind as very light scratches and just a light hazing. This would not be visible to the naked eye in natural light or poor lighting conditions.

In the April issue of Auto Laundry News, we discussed the importance of polish in your arsenal of car care products. We posed the question: What makes a great polish? As an answer, I suggested 13 specifications that a polish would need to meet to be considered great. This month, we take a closer look at the abrasive content of polish products, and offer information on how to objectively test one polish against another.


The main “ingredient” to look at in a polish is the abrasive. The type of abrasive and its size, hardness, and shape will determine what that polish will ultimately do to the paint surface.

The larger the abrasive, the more aggressive it will be on the paint surface. Abrasive particles are measured in “microns,” a metric unit of measurement. A micron equals one thousandth of a millimeter. Can’t gage how small that is? Well, an average human hair is 50 microns thick. The abrasive size in some polishes may be 7 microns, 5 microns, 3 microns, or less. This is why with today’s polishes you can rub the product between your fingers and never feel the abrasives — it’s no longer the way to determine how gritty or course the polish is. You will never feel the difference between a 7-micron abrasive and 3-micron abrasive on your fingers, but you will see the difference on the paint surface.

The particle shape also makes a difference in how aggressive the product is. An abrasive shaped like a diamond or spur with many pointed edges will be far more aggressive than a round or spherical abrasive. Sometimes even the smallest size abrasive may still have sharp, biting edges and can still behave aggressively. So size does matter, but the shape plays an important role in the aggressiveness of a product. Then there are products that have “diminishing” abrasives which means they actually break down, diminish in size, and turn far less aggressive as more passes are made with the buffer.

The “hardness” of an abrasive also makes a huge difference. An abrasive that is extremely hard will mar and cut the paint more than an abrasive that is softer and breaks down while buffing.

Some common examples of abrasives are Aluminum Oxide, Kaopolite, Tripoli, and Diatomaceous Earth, just to name a very few. Even within these categories there are many different types of abrasives. Combine these with size, shape, and hardness variables, and you can quickly see that there can be any number of different polishes that will do any number of different things to a paint surface.

I show some of these raw abrasives to detail students in my classes. When you open the container and shake some out onto a piece of paper, the abrasives look anything but abrasive. They all look and feel like powder. Even when you pick them up and rub them between your fingers, you will not feel much grit. However, when you take any of these abrasives and rub them onto the paint, they will most certainly scratch, mar, and haze the surface. Finding the correct abrasive can prove to be almost impossible. All will work to some degree, but if you are looking for perfection, it’s very difficult to find the right one.

The Recipe
Once you think you have the correct abrasive for the product, putting it together is another project. Making sure a polish formula is stable and mixed correctly with the proper solvents, oils, water, and any other kind of additives is a very tricky challenge. Sometimes the adjustments that need to be made are minute in terms of percentage of an ingredient. Combining different abrasives can either help or hurt a formula.


We have all probably done this before. We have taken some of this, some of that, mixed them in another bottle and made what we thought was the perfect polish. It just doesn’t work that way — and it’s not recommended. Don’t be a “bathtub chemist.” Mixing your own concoction just won’t work. Ingredients that were made for one product may not blend well with another product. Abrasives may clump together and produce a much more aggressive product than you may have thought. Solvents may not be compatible and the product may separate. I cringe when guys tell me that they make their own products. Don’t do it!

The bottom line is that there are many good polishes available that will work well. However, to create absolute perfection in a polish, it takes hundreds of hours of testing and development and dozens upon dozens of samples to get it there.


Forget the brand names and forget all the technical stuff I just talked about. The way to judge a polish is by the 13 specifications I set down in Part I of this article (Auto Laundry News, April 2009, page 86) based on ease of use and performance. But to really check to see which polish does the best job you have to have certain controls in place if you decide to test for yourself.

You need to work with the same kind of buffing pad for each polish you want to test. The pad should be fully clean to start. You must be working with the same buffer and work it at the same speed for each test sample and use the same buffing pressure. You must be working on the same paint surface and on a dark color. I do all my testing on a black clear coat that is soft in nature so I can see everything that is happening to the paint surface. I also do all my tests side by side and I tape off the area where one sample ends and the next sample begins. I also place the same imperfections in the panel. If I am testing the level of aggressiveness, I put a certain grade of sand scratch in the panel side by side. They are equal so I can judge which sample does better. If I am testing to see how well the sample will remove swirl marks, I buff the entire area evenly with a pad and another product that I know will leave swirl marks behind in the paint surface. I buff in these swirls equally on both sides of the test area.

Once my controls are set, I start to test the samples. I test sample “A” right next to sample “B” and look closely. I used to just look with the naked eye. But as the samples get better and more similar to each other, that method is not accurate. I used to take my test panel out into the direct sunlight and look at the results. But some days the sun is too bright. Some days it may be poking in and out of the clouds. And never is it at the same angle in the sky every single time. And of course some days there is no direct sunlight at all. The sun is not a good control.

What I use now is a very special light that simulates direct sunlight and I shine it directly over my test panel and I move it around and carefully look to see what each sample has accomplished. I turn all other lights off in my shop and only use my special test light. Now I can control the angle and the height of the light and I shine it over both test areas and I can see which sample is better.

Best Against Best
As polish samples get better and better, even this testing is difficult. I look for marring of the clear coat, any hazing, any swirl marks left behind, and the level of gloss. Sometimes there is a distinct difference but as you get closer to a more perfect polish, the distinction becomes less clear. But this really is the only way to objectively test anything. I not only test samples side by side, I test the best samples against other leading polishes side-by-side and judge objectively.

In the end, all the hard work is well worth it, not only in identifying a great polish but in learning all the things that go into making a polish, the chemistry involved, and how monumentally difficult it really is. So, if somebody tells you that they are using the “best” polish out there, ask them how they came to that conclusion. Ask them how they tested it, and if the polish meets all of the 13 criteria I have listed in this article. If you need to conduct some of these tests yourself to find the best polish, it’s worth the trouble. Your customers will be happy you did.

Kevin Farrell owns and operates Kleen Car (, a full-service auto-detailing business located in New Milford, NJ. Kevin is also an instructor for a detailing program he developed for, in and in conjunction with, BMW of North America. His background includes auto dealership experience and training through DuPont, General Motors, and I-Car.

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