During and after a smoky fire, soot settles on every surface, including walls. Your first impulse may be to clean this off just as you would dirt or dust---with a damp cloth or sponge. However, using an ordinary sponge first will only smear the soot and add to the cleanup process. Special sponges, available at many hardware stores, are made for cleaning soot off walls and most other surfaces. They are used dry and will remove much of the surface smoke damage before you use a liquid cleaning solution.
Put on face mask, safety glasses and old clothing or protective clothing and ventilate the room well. (Ventilating is important for removing any remaining airborne soot particles that would eventually on walls and other surfaces.)
Wipe down walls from top to bottom, using a chemical dry sponge. Use one steady swiping movement rather than rubbing.
Wipe down the painted wall once more, using clean dry chemical sponges. This is to remove remaining soot which, though not as visible, is probably still present on the wall.
Mix 118ml of soot cleaning solution to one gallon of water in a clean plastic bucket. Fill an additional bucket with plain water. Dampen regular sponges in the solution and wipe down wall. Rinse the sponge frequently in plain water to remove excess soot.
Dry walls well with towels. Wipe them dry using the same downward strokes as you used with the sponges. This helps prevent streaking. If you notice soot on the dry towels, wipe down the wall with damp sponges again.
Change sponges frequently for maximum soot removal. For high areas, you can avoid using a ladder by attaching on of the special dry sponges to a sponge mop handle. Cloth baby diapers work well as alternatives to towels for the wet cleaning and drying of painted walls.
Don't wet down the sooty wall or the chemical dry sponge. Doing so will embed the soot into the wall's painted surface, making it more difficult to remove. Soot may contain many harmful chemicals and heavy metals, such as lead. Use safety glasses and protective gloves and masks. After cleaning soot from walls, wash your clothes and shower to remove residual soot on your skin. Alternatively, wear a Tyvek protective suit over your clothing.