What type of paper should be used to matt the paintwork before painting? - Key tips

 

Want to give your car a new shine, but don't know where to start? The most important step in the car body painting process is matting the paint. It is this stage that determines the durability and aesthetics of the new coat of paint. With proper surface preparation, you can achieve a result that will surprise not only you, but also others on the road.

In this article, you will learn:

• Why is matting paint necessary?
• What kind of paper should be used for matting paint? Choosing the right grit
• Paint matting techniques - dry or wet?
• Does acrylic primer need to be matted?
• Summary - how to matt paint before painting?

Why is matting paint necessary?

Matting paint is not just a cosmetic procedure - it is important for the proper course of the painting process. The main reasons for matting are:

• improving the adhesion of the new coat of paint - without proper matting, the new paint may not adhere properly or form air bubbles;
• removing minor scratches and unevenness – smoothing the surface before painting makes the paintwork more precise;
• removing dirt and wax residues – even minor dirt can negatively affect the final result.

Whether you are painting over old paint or applying a new primer, proper surface preparation is crucial for the durability of the paint.

What sandpaper should you use to matt paint? Choosing the right grit

The grit of the sandpaper is an important part of the matting process. The choice of grit depends on the effect you want to achieve and the condition of the surface.

1. Preparing the car body for filling

If the surface needs to be repaired and levelled before painting, use a lower grade sandpaper:

• P100-P150 - for manual processing,
• P80-P100 - for a mechanical sander.

This allows for thorough removal of old coatings and preparation of the surface for the filler layer.

2. Sanding and smoothing the filler

Filled surfaces require gradual smoothing, so it is best to use the following grades:

• P80-P120 - for initial treatment,
• P150-P180 - for final shaping,
• P240-P320 - for smoothing before applying the primer.

3. Matting the acrylic primer

The primer must be properly prepared before painting. Depending on the matting method, different grades are used:

• P400-P500 - for dry sanding by hand,
• P600-P800 - for wet sanding.

To avoid unevenness and scratches, it is advisable to use sandpaper with a finer grade for matting paint and to regularly check the surface for dirt particles.

4. Matting old paint before painting

If a new coat of paint is to be applied to old paint, it must be properly prepared:

• P1000-P1500 - for wet matting by hand,
• P800-P1200 - for matting with a sander.

The use of appropriate cushioning pads for the sander prevents the paint from being rubbed off the edges of the car body.

Paint matting techniques - dry or wet?

Matting can be done in two ways: dry and wet. Each of these methods has its advantages and is used in different cases.

Dry matting

• Mainly used for matting the primer and surfaces prepared for priming.
• Sandpaper with a grit of P400-P600 is used.
• Allows for quick removal of unevenness.

Advantages

• Faster than wet sanding.
• Easier control over the progress of work.

Disadvantages

• More dust, need for vacuuming.

Wet matting

• Used for final smoothing of the primer and matting of the paint before applying a new coat.
• Sandpaper with a grit of P600-P1500 is used.
• Minimises the risk of scratches and abrasions.

Advantages

• Prevents clogging of the sandpaper.
• Lower risk of surface damage.

Disadvantages

• Requires frequent rinsing of the paper and checking of the surface.

When matting paint, it is best to use the wet method, as this allows for an even surface without the risk of deep scratches.

Does acrylic primer need to be matted?

Acrylic primer must be matted before applying paint to ensure proper adhesion of the new coating. Does acrylic primer need to be matted? Yes, this is necessary because a non-matt surface can lead to paint peeling or uneven coverage.

Dry matting of the primer requires P400-P500 sandpaper, and wet matting requires P600-P800 sandpaper. It is advisable to use high-quality sandpaper for matting the varnish to avoid streaks and scratches.

Summary - how to matt the varnish before painting?

Matting the varnish is an important step in the varnishing process. To ensure the best finish:

• choose the right sandpaper grade depending on the stage of work;
• use dry matting for primer and filler, and wet matting for paint;
• pay attention to accuracy - an unevenly matted surface can cause problems with paint adhesion;
• choose high-quality paint products, e.g. from proven paint manufacturers such as Multichem, to achieve the best results.

Proper preparation of the car body is essential for a durable and aesthetic paint finish, so it is worth spending the right amount of time and attention on this stage.