HOW TO PROPERLY PREPARE A CAR SURFACE BEFORE PAINTING

In 90% of cases, the final result of car painting depends on surface preparation. Even the highest-quality paint cannot hide a poorly prepared surface, which is why proper preparation is the most important stage in the entire painting process.

In this article, we explain step by step how to properly prepare a car surface before painting to ensure good adhesion, even color coverage, and long-term durability.

Step 1 – Washing the surface and removing dirt

Before any sanding begins, the surface must be completely clean.

You will need:

  • car wash detergent
  • clean water
  • thorough drying of the surface

👉 Dirt, sand, and road salt can cause scratches and interfere with further processing.

Step 2 – Inspecting old paint and defects

After washing, inspect the surface for:

  • scratches
  • rust
  • paint peeling
  • surface imperfections

If rust damage is present:

  • rust must be completely removed
  • repainting over rust is not sufficient

Step 3 – Sanding (the most important stage)

Sanding ensures proper paint adhesion to the surface.

Common grit ranges used:

  • P80–P120 → for rust and old paint removal
  • P180–P240 → for surface leveling
  • P320–P400 → before priming
  • P500–P600 → before painting

⚠️ Sanding must be even, with no glossy spots left behind.

Step 4 – Degreasing

After sanding, the surface must be thoroughly degreased.

Degreasing:

  • removes oils
  • removes silicone residues
  • prevents the “fish-eye” effect during painting

👉 Use a dedicated automotive degreaser, not household cleaning products.

Step 5 – Priming

Primer:

  • ensures adhesion
  • protects metal from corrosion
  • levels minor surface imperfections

Primer selection depends on the surface:

  • for metal – anti-corrosion primer
  • for plastic – plastic primer
  • for leveling – filler primer

After priming:

  • lightly sand the surface again
  • degrease before painting

Step 6 – Final inspection before painting

Before applying paint, make sure that:
✔️ the surface is matte
✔️ there is no dust
✔️ there is no grease
✔️ there is no moisture

👉 If everything is correct at this stage, the final result will also be high quality.

Most common surface preparation mistakes

❌ insufficient sanding
❌ skipping degreasing
❌ painting over glossy surfaces
❌ “painting over” rust

These mistakes lead to:

  • paint peeling
  • uneven color
  • reduced durability

Where to find surface preparation materials?

PROMIX.lv offers sanding materials, primers, degreasers, and other automotive painting products required for proper surface preparation before painting.

👉 By following our Car Painting Tips, you’ll also learn about correct painting and clear coating techniques.

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