Kelp harvesting during World War I peaked in 1919 when 400,000 wet tons were used to make potash for gunpowder and fertilizer. In the 1930s the food, pharmaceutical, and scientific communities began extracting algin, a thickening, stabilizing, suspending, and gelling agent. Algin is an additive used in a wide variety of dairy products, frozen foods, cakes, puddings, salad dressings, shampoos, and toothpastes. It smoothes and thickens ice cream, emulsifies salad dressing, and keeps pigments uniformly mixed in paints and cosmetics. Additionally, some mariculture farms hand-harvest kelp to feed abalone. In the 1980's alone, kelp harvesting supported an industry worth more than $40 million a year, and in 1993, more than 4,700 wet tons of kelp were extracted from the Monterey Bay National Marine Sanctuary.