Should I sand after priming?

When It Makes Sense

• Good fit: You are working on a smooth‑finish interior wall where the primer has raised the texture or left brush marks, and you need a flawless base before applying a low‑sheen or semi‑gloss paint.
• Good fit: The project uses a high‑build, oil‑based primer on a previously glossy surface, and a light sand can help the next coat of paint bond better without causing the primer to flake.

When You Should Avoid It

• Warning sign: You are using a thin, water‑based primer on drywall and the surface is already fully cured; aggressive sanding can remove the primer entirely, compromising coverage.
• Warning sign: The substrate is delicate (e.g., soft‑wood paneling, MDF, or a freshly primed plaster) where sanding could damage the material or create dust that settles into pores.

Pros and Cons

Pros

• Reduces brush or roller texture left by the primer, resulting in a smoother final paint appearance.
• Improves mechanical adhesion for the topcoat, especially when using high‑gloss or enamel paints that demand a slightly roughened surface.

Cons

• Adds an extra step, increasing labor time and cleanup, which may not be justified for low‑visibility areas.
• Risk of over‑sanding can strip the primer, requiring re‑priming and potentially leading to uneven coverage or visible patches.

Decision Checklist

• Is the primer fully cured and compatible with sanding (e.g., latex or oil‑based primer designed for sanding)?
• Will the finish you plan to apply benefit noticeably from a perfectly smooth substrate?
• Do you have the right grit sandpaper (typically 220‑320 grit) and proper ventilation to manage dust safely?

Alternatives to Consider

If you want a smooth finish without sanding, you can apply a second thin coat of primer to fill low spots, use a high‑quality “self‑levelling” paint, or opt for a primer‑and‑topcoat system that tolerates minor texture. For delicate substrates, a light‑touch “wet‑sand” with a damp sponge can smooth the surface without abrasive damage.

Final Recommendation

Sand after priming when you need a near‑perfect surface for a high‑gloss or critical finish and you’re using a primer that cures hard enough to withstand gentle sanding. Skip or minimize sanding on soft or delicate materials, on surfaces already smooth enough, or when time and effort outweigh the visual benefit. When in doubt, test a small inconspicuous area first, and consult a professional painter for high‑value projects or unusual substrates.