Reply To: Laundry detergent needs a hechsher? Why?

Because in the past animal fats (e.g. lard, fat derived from pigs) was used in making soaps and detergents. Many people do not like the idea of washing their clothes or eating on a table cloth that may have been washed with treff soap. Therefore many kosher consumers want laundry detergent to have a hecksher (and overall, many consumer was soaps that do include dead animal parts in them). Since the consumers want detergent with a hecksher, the companies that give hecksherim meet the demand.