What is a medium polish

A medium polish is a polishing product with a certain level of cutting. It will not remove RDS or severe surface imperfections, but it will will remove swirls, oxidation and several others. It is the most common step after cutting/compounding and if followed up by a finishing polish.

Why a medium polish

When polishing a surface, you are essentially removing a very fine layer of that surface. By removing as much of the surface as the deepest imperfection, you end up with a smooth surface that reflects light in the same way all around. The amount of surface you remove is often considered the “grade” of “level of cut”. However, the higher the level of cut, the lower the perfectly smooth surface when looked at a microscope. A cutting polish or compound will remove more imperfection in one go, but will also leave surface that is still not microscopically smooth and perfectly flat. A medium polish will remove a bit less in one go, but will reach a smoother finish. A finishing polish will remove fairly little from the surface but will finish with a very smooth and flat surface.

The general recommendation is to always go from rough to fine in small steps. If it is necessary to polish with a cutting compound, you should follow up with a medium polish. After the medium polish, you follow up with a finishing polish.
However, it should be noted that there are exceptions due to the choice in polishing pad, the polishing technique, the polishing machine and the product that is being used. For example: Kevin Brown has developed a technique that allows for high cutting with a finishing polish by using a certain technique.

Difference with other polishes

Although products can differ between manufacturer, it is generally accepted that a medium polish has a lighter type of polishing agent. In many cases these are very tiny grains with a certain shape or size. While polishing, these agents are rubbed over the paint and slowly “scratch” away small parts of the paint. This is an extremely fine version of sanding. Although the finish looks very good to the naked eye, a microscope might reveal a surface that is still not perfectly flat or smooth. If the polish has been broken down properly while polishing, you might end up with microscopic lines in the paintwork, which is called “micromarring”.

Difference in medium polish

With many products, there is a type of benchmark. A certain unit to compare something with in order to determine in which category it fits. Unfortunately, this doesn’t exist for the world of detailing. This means that the level of cut can differ per manufacturer. In some very extreme cases, this can lead to a medium polish that would be a cutting polish compared to another manufacturer. There is (yet) no benchmark to compare these products with.
In other cases, it can differ by the type of polish. The main differences are DAT or SMAT polishes. A DAT polish will break down gradually and slowly increase in level of finish while the level of cut decreases. However, SMAT products are designed to hold on to their level of cut, regardless of the amount of time you are working with it. A medium DAT polish will slowly break down and reach the performance of a finishing polish. The main downside with this is the amount of paint particles that will slowly clog up the polishing pad, which has a negative effect on the level of the finish.
Some manufacturer solve this problem by added a step in the level of cut. Instead of a finishing polish, a medium polish and a cutting polish, they introduce a light medium polish and a high medium polish.

Other variables that play a part in the finish

Just the level of cut from a polish is not the only variable that plays a big part in the finish. You also need to consider the type of pad that is being used, the polishing machine and various other factors. However, most manufacturer aim to make the polishing process as easy as possible. More and more manufacturers are developing their products in such a way that you should get reasonably even result in different situations. A medium polish should give a very similar result, even if you change the pad.