Sir William McKercher in Assam, India, invented the CTC process in the 1930s. The process spread in the 1950s throughout India and Africa. Today, most black tea produced around the world uses the CTC method. The finished product results in tea well-suited for tea bags, is strongly flavored, and quick to infuse. Crush, tear, curl (sometimes cut, tear, curl) is a method of processing black tea in which the leaves are passed through a series of cylindrical rollers with hundreds of sharp teeth that crush, tear, and curl the tea into small, hard pellets. This replaces the final stage of orthodox tea manufacture, in which the leaves are rolled into strips.
Tea produced using this method is generally called CTC tea or mamri tea. CTC teas generally produce a rich red-brown color when they are boiled by the Indian method. The drawback of the CTC method is that it tends by its nature, and unfortunately by adulteration, to homogenize all black tea flavors. In the process of crushing, tearing and pelletizing the tea leaves, pressures and stresses occur which break down the cells, releasing large amounts of the phytins that normally oxidize to produce black tea’s mahogany color. Since, regardless of origin, CTC teas in their dry form are generically "tea-like" in aroma, and of similar pelletized appearance, it is easy to adulterate a more expensive CTC-type tea with inexpensive and generally mild lowland teas of the same process. Whole and broken leaf teas by contrast are quite varied in appearance, making adulteration more difficult.