Although black tea production techniques were first developed in China, they are now international methods that come from a variety of countries. Traditionally, black tea production involved four distinct steps: withering, rolling, oxidizing and drying. The leaves are placed on bamboo racks to be wilted. Once they are soft enough, they are rolled in a manner that doesn’t damage or tear the leaf. The withered leaf is rolled so as to make it release the flavors and essential oils that will give the tea its final flavor and coloration. The shape of the black tea leaves is also influenced by the rolling process and this has an impact on the way the flavor spreads when the leaves are used for infusions. The rolled leaves are spread out in cool and humid rooms and exposed to oxygen for several hours, which causes chemical changes in the leaves and turns them from green to coppery red. Once the leaves are oxidized, they are dried – in hot works, by the Chinese tradition.