Combine 1 cup of ammonia, 1/2 cup of liquid laundry detergent and 3 gallons of warm water in a 5-gallon bucket.
Soak a nonabrasive sponge into the solution. Squeeze the sponge so that it remains damp.
Clean a small section of the stained wall at a time. Rinse the sponge in clean water and continue soaking it in the solution as needed.
Dry each section of the wall with a towel.
Mix 1 tablespoon of trisodium phosphate with 1 gallon of warm water. Add 2 tablespoons for heavy soot removal.
Dip a nonabrasive sponge in the solution. Wring out the excess solution so that the sponge remains damp.
Wipe the walls down with the cleaning solution. Rinse the sponge in clean water when it becomes dirty.
Dry the water off the wall with towels.
Combine 1 cup of white vinegar with 1 cup of warm water in a spray bottle.
Spray the diluted vinegar on a small section of the wall.
Wipe the wall down with a washcloth to remove the soot and lingering odors.
Dry the wall with a towel.