A number of methods may be employed to make soap, but all are based on the same principle of operation. Salt is added, and the soap then forms a light curd that floats to the surface. Glycerol, a valuable byproduct, can be distilled from the liquid residue. It is thoroughly churned, poured into huge frames, cut with wires, shaped, and stamped. Hard-milled soap is run over chilled rollers and is scraped off as chips which are rolled into ribbons, cut, and shaped.
Soap is marketed also as chips, flakes, and beads and in powdered form.
Soap powders, as distinguished from powdered soap, contain builders that assist in rough cleaning. Soaps differ according to the lathering properties of the fat or oils and according to the alkali employed. Aluminum, calcium, magnesium, lead, or other metals are used in place of sodium or potassium for soaps used in industry as paint driers, ointments, and lubricating greases and in waterproofing. Click here to see documents from Electric Library, a pay service. Listing from Electric Library , a pay service.