(3).
Sources of harshness. The history of fabric softeners in
consumer use is associated with the conversion of laundry
detergents from tallow-based soaps to synthetic bases, or
syndets. Since ancient times, clothes have been washed
with soaps (sodium salts of fatty acids) by hand, and later
with a mechanical washing machine. Around 1945, synthetic
detergents, primarily based on alkylbenzenesulfonates
as well as other secondary surfactants, began to
rise in prominence for machine washing in North America.
The new generation of laundry detergents was formulated
with builders, that is, sequestering agents such as
phosphate, carbonate or citrate, to reduce the deposition of
insoluble calcium and magnesium salts of soap and alkylbenzenesulfonates.
These insoluble calcium and magnesium
salts cause redeposition of soil, resulting in a gradual
buildup of a dingy, gray film on light-colored fabrics