Identify the surface and follow the current instructions for your exact products. Do not sand or strip uncertain old coatings. Read the safety guide before disturbing materials.
The higher the number, the finer the scratch
Most UK abrasive sheets use a P grade. P80 cuts much more aggressively than P240. Coarse paper removes material quickly but leaves scratches that need refining. Fine paper is for smoothing or denibbing, not for forcing a failing coating to become sound.
Start with the least aggressive grade that does the job. On a flat repair, wrap the paper around a block so you level the surface rather than hollowing out the soft spot with your fingertips.
| Grade | Typical job | What to watch |
|---|---|---|
| P80 to P100 | Initial shaping of suitable bare timber or hard filler | Coarse scratches can show through paint. Not a default for plaster or old paint. |
| P120 to P150 | Refining timber and levelling suitable dry repairs | Use a block on flat repairs. Keep edges and mouldings intact. |
| P180 | Fine preparation of sound painted woodwork | Aim for a uniformly dull surface, not complete removal. |
| P220 to P240 | Light denibbing between compatible, sufficiently dry coats | Use only where the product permits sanding. Do not polish the surface. |
Let the abrasive do the work
Pressing harder rarely improves the result. Replace clogged sheets, keep your pressure even and work with the grain on bare wood. Use a flexible pad gently on a profile rather than flattening its detail.
- Confirm the material is safe to disturb and the coating or filler is dry enough to sand.
- Test the chosen grade on an inconspicuous area.
- Remove only the roughness or material needed, then refine coarse scratches with a finer grade.
- Control dust at source, remove residue appropriately and check the surface under side lighting.
- Check that the surface is clean and dry before the next coating.
Between coats is a light touch
Denibbing means removing tiny raised particles, not sanding the finish away. Some paints need no sanding between coats inside their recoat window; others specify an abrasive and timing. Follow that system. Sanding a soft coat creates rolls of paint and damage rather than a smooth foundation.
Common mistakes
- Using coarse paper on a finished wall because it feels quicker.
- Overworking corners and cutting through thin veneers.
- Sanding unknown old paint or textured coatings.
Do not dry sand suspected lead paint or disturb possible asbestos. Stop and arrange competent assessment. Dust masks do not make an unidentified hazardous material safe to sand.
Sources & further reading
Original general guidance from Aethos, informed by the resources below. These references cover relevant safety, materials or techniques, not a specification for your property. Product examples are not paid recommendations.
- HSE: lead in construction (opens in a new tab)
Why disturbing older lead paint requires a planned, controlled approach.
- HSE: asbestos guidance (opens in a new tab)
Identifying potential asbestos risks before disturbing building materials.
- Zinsser: Bulls Eye 1 2 3 technical information (opens in a new tab)
An example of why preparation, substrate suitability and recoat instructions are product specific.