Dust nibs in a finish

Likely causes

The causes the most sources give come first.

1. Dust in the air, or left on the piece, settles in the wet finish.

   3 sources agree , sources [1, 2, 3]

2. Dirt carried by the tools: a dirty brush, tack cloth or spray gun.

   Two sources: Chemcraft and Mohawk (RPM) , sources [2, 1]

How to tell which

None of the sources we read says how to tell these causes apart. Check each one against how you finished the piece.

The fix

1. Once the coat is dry, sand the flaw level with fine paper, wipe off the dust and put on another coat. The makers name 220 grit (Minwax), 220–320 (General Finishes) and 400 for sprayed lacquer (Target).

   3 sources agree , sources [3, 4, 5]

2. On the final coat, let the finish cure, then sand the flaws off with very fine wet-or-dry paper and polish it.

   Two sources: General Finishes and Target Coatings , sources [4, 5]

Next time

1. Vacuum the dust off, then wipe with a tack cloth or a damp cloth before each coat.

   3 sources agree , sources [3, 6, 5]

2. Finish in a clean room, away from where you sand and saw.

   Two sources: Mohawk (RPM) and Chemcraft , sources [1, 2]

Often comes with

• Bubbles in polyurethane
• Brush marks

The finishes it applies to: oil-based polyurethane, water-based polyurethane, wipe-on polyurethane, spar urethane, lacquer. Every other problem: the finish troubleshooter.