How do you get coal dust off walls to paint them?

Hi Marylou, the best product I've ever used to remove various stains from walls is TSP (trisodium phosphate). You can buy it in dry form or liquid and mix with water. Use a clean soft cloth to clean the walls with the mixture. You'll be amazed how well it works. Then get clean, clear water and use a clean cloth to rinse the walls well. Then you can fill in any nail holes or dings in your walls and sand slightly and then mask off and paint the walls in the color of your choice.

Coal dust stays because of oil in it. Krud Kutter original concentrate will cut it. Follow directions to mix with water. Spray on, let it set a minute, wipe off. No scrubbing.

Thank you

Leah has the answer. It's a mess, I had that too. Sorry.

Try vacuuming it off, or sweeping, first, to get any loose dust off.