How do you grind car paint?

It is also important to remember that matting does not only include work. Scratches on the car body can be a headache for many car owners. Fortunately, there are ways to remove them in the home garage, using only water paper or polishing paste. However, it is worth preparing for the work beforehand, for example, by learning how to remove the matt finish.

How thick are all coatings?

The surface of every vehicle's body is covered with a paint coating system consisting of a primer (anti-corrosion), a colour base and a clear coat. In the case of surfaces that have not yet been repaired, the total thickness is about 100-130 microns in Japanese cars, for example, and up to 200 microns in cars produced by German factories.

Car owners are often horrified to see a single white scratch. This often means that the dent has penetrated the top layers and reached the anti-corrosion layer, the primer. Fortunately, this is not always the case, because the polished clear coat crumbles like chalk when damaged. In this case, the scratch can be easily removed by matting the paint with water paper. Sanding the surface of the car body will reduce the thickness of the clear coat and make the car look less shiny at the beginning of the job, but after polishing, the whole will regain its mirror effect.

A way to deal with deep scratches

When removing scratches and sanding car paint, it is important to have a coating thickness gauge. This device must be in perfect working order to ensure that the entire process is successful. This will prevent mistakes when estimating the coating thickness of the part to be repaired.

In order to make it easier to polish the paint with polish later on, the surface to be repaired should be lightly polished during matting. Of course, the depth of the scratch must be taken into account and it must be determined whether the car body has been repaired before. It is common knowledge that the paint thickness on new cars coming off the production line is getting thinner and thinner, and thus aggressive sanding will damage the paint layer and result in the need to repaint the entire part. However, we can allow ourselves to gently sand down the coating to eliminate visible damage and restore the entire surface to its original splendour.

Which paper is best to use?

The selection of work accessories is best started with the choice of the right sanding block. Among the many available on the market, we can find copies of different hardnesses, but the safest choice will be an optimally soft cube, because a completely hard one may be too aggressive to remove a few scratches and consequently cause more problems than expected benefits. Softer blocks will allow for more subtle interference with the coating, helping to achieve an even structure by matting the car paint.

When looking for water paper, you should choose one that will work extremely smoothly on the surface. It must not cause depressions, which would be extremely difficult to eliminate during the polishing stage. The key issue is to choose the right gradation, which should depend on the car body and the degree of damage:

• For delicate scratches on soft car paint, it is best to use a 2500-3000 grit wet sandpaper. This will allow the entire process to slowly and gently remove only a small layer of clear coat.
• A harder and thicker surface can be matted without hesitation with a stronger water paper with a grain size of 2000, and in the case of deep scratches even from 1500. However, it is necessary to carefully verify whether the treated surface allows the use of a higher grain size.

Above the scratch itself, as this would leave a dent in the car body. It is best to make circular movements with water paper on and around the damage. When working on car paint, it is a good idea to use a gauge from time to time to reduce the entire surface structure evenly. When the scratch starts to disappear during matting and we work with a harder sheet, we use an increasingly finer one. This way, we smooth out the damage and can move on to polishing. This last stage of the work allows the treated part of the car body to regain its full shine by using polishing paste.