K.C. Body Shop Supply

Call Us (773) 306-2805

How to: Prevent and Fix Sanding Marks on a Paint Finish

How can I remove the grooves in my car paint?

You’ve finished painting your car, but you notice scratches or grooves in the surface. These sanding marks come from the sanded substrate below the finish. The marks can be eliminated by sanding and refinishing.

In this article, I’ll answer common questions about how to prevent sanding marks and eliminate them when it happens.

  • What are sanding marks?
  • What causes sanding marks?
  • How can I repair a surface showing signs of sanding marks?
  • How do I prevent sanding marks?

What are sanding marks?

Sanding marks (also called streaked finish or sand scratches) are dark or streaked marks that look like sand scratches in the paint film.

What causes sanding marks?

Sanding marks happen when scratch marks or distorted metallic/mica flakes appear close to the surface of the paint surface because:

  • You only did a single-stage of sanding or sanding of a basecoat metallic finish before applying the clearcoat.
  • You sanded a single-stage metallic finish just before buffing.
These are fine sanding marks.

How can I repair a surface showing signs of sanding marks?

To fix sanding marks, follow these two steps:

  1. Allow the finish to dry
  2. Sand and refinish.

How do I prevent sanding marks?

Preventing sanding marks requires knowing when and how to sand basecoats and single-stage finishes:

  • Avoid sanding basecoat finishes before clear coating. If sanding is necessary, apply additional color following the label directions.
  • When sanding single-stage finishes, confine the sanding to minor imperfections (nib sanding rather than entire panels). For the best results, use 1500 or finer grit sandpaper.

Doing these things will prevent sanding marks from appearing on your paint finish and give you the smooth, glossy surface you were aiming for.