Although ash deposits are the most troublesome and the most common, soot deposits are also of major concern. A soot deposit is one which consists of unburned carbon. Soot deposits are undesirable not only because of their own accumulation but also because of their binding effect on other deposits.

Unburned carbon - soot - represents a major loss of fuel heating value and money. The formation of soot deposits is due to incomplete fuel combustion. This situation could be improved through the use of a combustion catalyst or improved atomization. If soot deposits are a problem, WSF should be used.

WSF will prevent the formation of soot deposits by improving combustion conditions and driving the combustion reaction to completion. Any soot that does form will have its ignition point lowered by WSF and will burn off.