Dirt, dust, grime and soot are all things that can blow on and build up on your house. These elements attach themselves to all types of house finishes including vinyl siding. Removing soot from vinyl siding is easy. All you need is the correct detergent, a little elbow grease and the right brush.
Mix in a large bucket a solution of two-thirds cup all-purpose household cleaner (Spic & Span or Soilax), one-third cup powdered detergent and 1 gallon of warm water. Agitate the mixture by stirring it with a long-handled brush. Wear rubber gloves, safety goggles, boots and a apron or other cover up.
Dip the brush into the solution and apply some of the mixture to the area of vinyl siding where the soot is present. Let the mixture stand on the soot for at least three minutes.
Scrub slowly to work the solution into the soot. Do not rub harshly—this will create a "shine" on your siding. Dip the brush back into the mixture and continue scrubbing until the soot is gone. Work in sections if there is a lot of soot to remove.
Rinse the vinyl siding with a water hose that has a sprayer attached. Repeat these steps if the soot is heavy on the vinyl siding.