Answer
Swirls usually come from dust, worn abrasive, too much pressure, or moving grits too quickly. Clean the surface, use a fresh sheet, and refine one grit at a time.
Why it happens
A random orbital pattern can become visible when debris is trapped under the sheet or the previous grit marks are not fully removed.
Recommended grit
Return to the grit that removes the swirls, often 220 or 320, then refine with 400 and finer as needed.
Wet or dry
Use dry sanding for normal orbital sanding. Use wet sanding only on water-safe surfaces and with tools designed for that use.
Success check
The swirl pattern is gone and the surface shows a uniform scratch pattern from the current grit.
What to do
- Stop and clean the surface before continuing.
- Check the sheet for loading or damaged abrasive.
- Replace the sheet if it is worn or dirty.
- Return to 220 or 320 depending on swirl depth.
- Sand with light pressure and steady movement.
- Move to 400 after the swirl pattern is removed.
- Inspect before moving to finer finishing grits.
Avoid: Do not press down hard on a random orbital sander. Extra pressure can make swirl marks worse.