Coat the soot stain with baking soda, and leave the soot covered in baking soda for an hour. Baking soda draws embedded soot out of upholstery.
Vacuum the sooty baking soda using the vacuum’s attachment. Extract all soot and baking soda from the sofa.
Squirt 1 tbsp. of non-bleach dishwashing liquid into a pail. Mix in 2 cups of cool water.
Moisten a white cloth with the detergent solution. Damp the remaining soot with the moist cloth until the black powdery residue is fully removed. Never apply a soot-stained portion of the cloth to the sofa.
Dampen another cloth with cool water. Blot the previously soot-stained upholstery until the detergent is rinsed out.
Damp the wet upholstery with a white towel to rinse off all the soap residue.