Tracers, RIDS & Pigtails

Tracers = Deeper scratches left by the sanding process, usually in straight-lines because most people move their hand in a back and forth motion when wet-sanding.

RIDS = Random Isolated Deeper Scratches. These type of scratches come from normal wear & tear and there is no pattern to them.

Pigtails = These types of scratches look like a curly pig tail and are left in the paint by a DA Sander. Typically what happens is an abrasive particle gets trapped between the paint and the face of your sanding paper and because the backing plate that holds the sandpaper is moving in an oscillating fashion, it grinds the abrasive particle into the paint in a curly pattern that looks somewhat like the tail on a pig, thus the name.

All three types of defects are difficult to remove because in order to remove them you must level the upper surface of the paint with the lowest depths of the defect. That means removing paint and that's where it gets tricky.

See this article...

What it means to remove a scratch out of anything...