Machine dishwashing detergent tablets

A machine dishwashing detergent tablet comprising

• a) an inner layer comprising an ingredient selected from the group consisting of a nonionic surfactant and a mixture of the nonionic surfactant with hydroxycarboxylic acid;
• b) a barrier layer surrounding the inner layer, the barrier layer comprising an ingredient selected from the group consisting of a water soluble polymer a water-swellable polymer, a mixture of water soluble polymers, a mixture of water-swellable polymers, a fatty acid, a soap, a wax, and mixtures thereof;
• and
• c) an outer layer surrounding the barrier layer, the outer layer comprising a builder and an ingredient selected from the group consisting of about 0.05% to about 20% of an enzyme, a source of chlorine bleach in an amount which corresponds to from about 0.1% to about 20% of available chlorine,
• wherein the total amount of ingredients in the barrier layer and the outer layer is such that the tablet comprises
• A) about 10% to about 99% of a builder, and
• B) an amount of an alkaline source sufficient to provide a pH of a 0.1% solution by weight of the tablet of greater than 9.0 during a dishwashing cycle of a dishwashing machine;
• and wherein the disintegration rate of the barrier layer at a temperature in the range of from about 100.degree. F. to about 160.degree. F. in an aqueous cleaning environment of a dishwashing machine, and the relative thicknesses of the inner layer, the barrier layer and the outer layer are such that:
• (i) at water temperature in a range from about 100.degree. F. to about 160.degree. F., in the aqueous cleaning environment of the dishwashing machine, from about 6 to about 44 minutes is afforded prior to release of the ingredient of the inner layer, and
• (ii) all layers of the tablet disintegrate in the aqueous cleaning environment of the dishwashing machine by the end of a dishwashing session.