Polyphosphates gave renewed life to soap products at a time when surfactants were a threat though expensive, and these same polyphosphates spelled the decline of soap usage when the synergism between polyphosphates and synthetic detergent actives was recognized and exploited.

The market today for detergent builders is quite diverse. The best known field of application for builders is in heavy-duty, spray-dried detergent formulations for household use. These widely advertised products, which are used primarily for washing clothes, are based on high-sudsing, synthetic organic actives (sodium alkylbenzenesulfonates) and contain up to 50% by weight of sodium tripolyphosphate or a mixture of sodium tripolyphosphate and tetrasodium pyrophosphate. In the household market, there are also low-sudsing detergent formulations based on nonionic actives with about the same amount of phosphate builder; light-duty synthetic detergents with much less builder; and the dwindling built soap powders as well as soap flakes and granules, none of which are now nationally advertised. A well publicized entrant which has achieved success only recently is the built liquid detergent, with which the major problem today is incorporation of builder and active into a small volume using a sufficiently high builder/active ratio.

Hard surface cleaning in household application is represented by two classes of alkaline products: (1) the formulations made expressly for machine dishwashers, and (2) the general-purpose cleaners used for walls and woodwork. The better quality products in both of these lines contain phosphate builders. In addition, many of the hard surface cleaners used for walls and woodwork had their genesis in trisodium orthophosphate, which is still the major ingredient of a number of such products. Many scouring powders now also contain phosphates. These hard surface cleaners are discussed in Chapter 28.