Why does my sandpaper clog up so quickly?

Abrasive does not usually wear out — it fills up. The gaps between the grains pack with material, and once they do the paper burnishes rather than cuts, which generates more heat and packs it further.

What you'll need

• stearated or non-clog abrasive
• abrasive cleaning stick (optional)
• dust extraction

Step by step

1. Work out what is clogging it.Pale powder that brushes off is fine dust and normal. Dark shiny lumps welded to the paper are melted finish or resin, which means heat. Sticky smears mean the coating was not properly cured.
2. Let coatings cure fully first.Filler, primer and paint all sand well when hard and clog instantly when they are merely touch-dry. Wait longer than the tin's minimum, especially in cold or damp conditions.
3. Use stearated paper on paint and softwood.A soap-like dry lubricant in the coating stops the abrasive loading. It is usually the grey or white paper sold for paint and filler.
4. Connect extraction.Removing the dust at source stops it being pressed back into the abrasive by the tool. It is the biggest single improvement on a power sander.
5. Reduce the pressure.Pressing hard generates heat, and heat is what melts finishes onto the paper. Let the weight of the sander do the work.
6. Slow the sander down.If it has variable speed, a lower setting produces less heat on paint and plastics, and clogs far less.
7. Clean the abrasive rather than replacing it.A crepe rubber abrasive cleaning stick held against a running sander pulls the packed material out and restores most of the cut. It is cheap and lasts for years.
8. Watch for resin pockets in softwood.Knots and resinous areas will clog any paper. Scrape or cut them back first, or treat the knot with knotting solution before sanding.
9. Do not skip grades.Trying to remove heavy material with fine paper loads it instantly. Start with a grade coarse enough to actually cut.

Tips

• An abrasive cleaning stick costs little and roughly doubles the useful life of every disc and belt.
• If the paper is going shiny rather than dusty, you are pressing too hard or going too fast.
• Sanding paint that is a day old rather than a week old is the commonest reason for instant clogging.

Common mistakes

• Pressing harder as the paper stops cutting — A clogged abrasive cannot cut, so the extra force only produces heat, which melts more material onto the paper and burnishes the surface.
• Sanding paint or filler before it has hardened right through — Soft coating smears rather than powders. It fills the abrasive immediately and leaves a rough smeared surface that has to be redone.

If it doesn't work

Questions people ask