How to Remove Chalk from Plaster

The following method safely removes chalk from finished plaster (although it’s always a good idea to spot test before you begin). If you’re trying to remove chalk from unfinished or unpainted plaster, see the information below in the additional tips and advice section.

• Trisodium phosphate (TSP)
• Warm water
• Bucket
• Clean cloths/rags

1. Begin by mixing 1 tablespoon of TSP with 1 gallon of warm water in the bucket.
2. Mix well.
3. Moisten a cloth completely with the solution. Wear protective gloves if you’d like.
4. Use the cloth to apply the solution to the wall, scrubbing gently as needed.
5. Repeat until the wall is clean.
6. Rinse away any TSP residue with a second cloth dampened with clean water.
7. Dry the area with a soft cloth and allow it to air dry completely.

• If the wall is unpainted or unfinished plaster, do not apply water or other liquids. Instead, use a toothbrush (for textured walls) or a piece of fine grit sandpaper (for smooth walls) and brush or sand gently until the chalk comes off.  Plaster and chalk are most often made of the same substances so you merely need to remove the top layer of color to rid the plaster of the stain.