120 vs 150 Grit for Bare Wood Before Paint

For bare wood that will be painted, 120 and 150 grit can serve different jobs. In a comparable abrasive family, 120 is the coarser option for removing the remaining surface marks; 150 refines that scratch before the specified coating process. Neither number guarantees that rough stock is ready for primer.

Start with the paint or primer manufacturer's preparation instructions and the actual condition of the wood. This comparison does not apply to removing unknown old paint.

Let the defect choose the starting point

Inspect the clean board in low-angle light. Look for planer marks, dents, glue residue, cross-grain scratches, and raised fibers. A finer sheet may make the high points feel smooth while leaving those defects untouched.

If a controlled 150-grit trial removes the remaining marks efficiently and the coating instructions allow that starting point, there may be no reason to begin coarser. If it does not, return to an effective preparation step instead of pressing harder.

Deep dents and glue contamination need their own repair or cleanup decision. Sanding the surrounding wood down to a dent can change the part's dimensions.

A manufacturer example, not a rule for every coating

General Finishes' raw-wood preparation guidance gives 120 followed by 150 for wood that will be painted. Treat that as guidance within its finishing context and confirm the exact product directions for your project.

For a permitted hand-sanding trial, use 120-grit sheets for the removal stage and a clearly identified 150-grit 25-sheet pack for refinement. Quantity changes how often you restock, not how coarse the surface should be.

Work the face and edges deliberately

Use a suitable flat support on a flat face. Keep the work secure and make even, overlapping passes. Inspect corners and profiles separately; a flexible sheet can round a crisp detail faster than expected.

Clean between stages using the approved dust-removal method. At 150, the task is to replace the preceding scratch pattern while preserving the intended shape. If one deep line survives, locate its cause rather than repeatedly sanding the whole face.

The 150-grit guide explains its place in preparation. Stop at the coating's specified endpoint; polishing bare wood to a much higher number is not automatically an improvement.

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Test with primer and paint

Prepare an offcut from the same stock, including an edge if the finished part has one. Apply the actual coating system at its specified coverage and drying conditions. View it under the light in which the finished project will be used.

If scratches remain visible, determine whether they survived preparation or appeared during handling. If the primer raises fibers, follow that primer's sanding and recoating instructions rather than applying the bare-wood sequence again.

A successful 120-to-150 process ends with a clean, uniformly prepared surface and a passing coated sample. The painted result is the useful evidence; the feel of the uncoated board is only one check.