How to smooth a wall that has already been painted?

To smooth a wall that has already been painted, you need to clean the surface, remove any peeling parts, sand down imperfections, and then apply a smoothing compound. Careful preparation ensures a smooth wall before applying primer and new paint.

What equipment do you need?

Make sure you have:

• protective tarps;
• degreasing detergent;
• scraper or spatula;
• filling compound;
• smoothing compound;
• trowel;
• fine sandpaper;
• sanding block or drywall sander;
• mask, goggles, and gloves.

1. Check the condition of the old paint

Observe the wall before starting. If the paint adheres well, it is not necessary to remove it entirely.

However, scrape off any blistered, cracked, or flaking areas. Peeling paint provides a poor base for the compound.

If the coating is old and may contain lead, avoid sanding it without a prior diagnosis.

2. Clean the painted wall

Dust and then clean the wall with a suitable degreasing detergent. Pay close attention around switches, in the kitchen, and on frequently touched areas.

Rinse if the product requires it, then let it dry completely. Compound adheres poorly to greasy or damp surfaces.

3. Lightly sand the paint

Sand the wall to remove small imperfections and make the paint less smooth. This step improves the adhesion of the compound.

For a small area, a sanding block may suffice. To smooth a large wall that has already been painted, a drywall sander with suction allows for more consistent work and reduces dust dispersion. Start with suitable abrasive paper and without applying excessive pressure.

4. Fill holes and cracks

Slightly open non-evolving cracks, dust them, then apply a filling compound. Also fill any holes left by dowels and old fixtures.

Allow to dry for the duration indicated by the manufacturer before sanding the repairs.

5. Apply the smoothing compound

Spread a thin layer of compound with a wide trowel. Work in sections, crisscrossing your strokes, then immediately remove any excess.

A second coat may be necessary if the wall has many imperfections. Always respect the drying time between applications.

6. Sand the compound after drying

Once the compound is completely dry, sand it with fine abrasive paper. Make regular movements without staying too long in the same spot.

An adjustable drywall sander is particularly practical for large walls and ceilings. Combined with a vacuum, it improves working comfort and facilitates site cleanup.

Then run your hand over the wall with a light placed to the side: hollows and bumps become easier to spot.

7. Apply a primer before painting

Carefully dust the surface, then apply a primer compatible with the substrate. It evens out the absorption of the compound and improves paint adhesion.

Once the primer is dry, the wall is ready for its finish.

Mistakes to avoid

• Applying compound directly to a dirty or greasy wall.
• Covering peeling paint.
• Applying too thick a layer of compound.
• Sanding before complete drying.
• Pressing too hard with the sander.
• Painting the compound without a primer.

Frequently Asked Questions

Can you apply compound directly to a painted wall?

Yes, if the paint is clean, sound, and properly prepared. A glossy surface should be lightly sanded before applying the compound.

Do you need to remove all of the old paint?

No. Only remove parts that are blistering, flaking, or no longer adhering to the wall.

What grit should be used to smooth a wall?

The choice depends on the condition of the surface and the compound's recommendations. A medium grit can correct major imperfections, while a fine grit provides the finish before painting.

How to get a perfectly smooth wall?

Apply several thin coats rather than one thick coat. Check the result with a grazing light, correct any imperfections, then perform a final fine sanding.

Key takeaways

To smooth a wall that has already been painted, keep the sound parts, eliminate imperfections, then apply compound in thin layers. A drywall sander with suction is particularly useful for large surfaces: it facilitates consistent sanding before priming and painting.