Black tea

Varieties and names

Blends

Manufacture

1. After the harvest, the leaves are first withered by blowing air on them.
2. Then black teas are processed in either of two ways, CTC or orthodox. The CTC method produces leaves of fannings or dust grades that are commonly used in tea bags but also produces higher grades such as BOP CTC and GFBOP CTC. This method is efficient and effective for producing a better quality product from medium and lower quality leaves of consistently dark color. Orthodox processing is done either by machines or by hand. Hand processing is used for high quality teas. While the methods employed in orthodox processing differ by tea type, this style of processing results in the high quality loose tea sought by many connoisseurs. The tea leaves are allowed to completely oxidize.
3. ; Orthodox: The withered tea leaves are heavily rolled either by hand or mechanically through the use of a cylindrical rolling table or a rotovane. The rolling table consists of a ridged table-top moving in an eccentric manner to a large hopper of tea leaves, in which the leaves are pressed down onto the table-top. The process produces a mixture of whole and broken leaves and particles which are then sorted, oxidized and dried. The rotorvane, created by Ian McTear in 1957 can be used to replicate the orthodox process. The rotovane consisted of an auger pushing withered tea leaves through a vane cylinder which crushes and evenly cuts the leaves, however the process is more recently superseded by the boruah continuous roller, which consists of an oscillating conical roller around the inside of a ridged cylinder. The rotorvane can consistently duplicate broken orthodox processed black tea of even sized broken leaves, however it cannot produce whole leaf black tea. The broken leaves and particles from the orthodox method can feed into the CTC method for further processing into fanning or dust grade teas.
4. ; "Cut, tear, curl" : A production method developed by William McKercher in 1930. It is considered by some as a significantly improved method of producing black tea through the mincing of withered tea leaves. The use of a rotovane to precut the withered tea is a common preprocessing method prior to feeding into the CTC. CTC machines then further shred the leaves from the rotovane by passing them through several stages of contra-rotating rotors with surface patterns that cut and tear the leaves to very fine particles.
5. Next, the leaves are oxidized under controlled temperature and humidity. The level of oxidation determines the type of the tea; with fully oxidised becoming black tea, low oxidised becoming green tea, and partially oxidised making up the various levels of oolong tea. This can be done on the floor in batches or on a conveyor bed with air flow for proper oxidation and temperature control. Since oxidation begins at the rolling stage itself, the time between these stages is also a crucial factor in the quality of the tea; however, fast processing of the tea leaves through continuous methods can effectively make this a separate step. The oxidation has an important effect on the taste of the end product, but the amount of oxidation is not an indication of quality. Tea producers match oxidation levels to the teas they produce to give the desired end characteristics.
6. Then the leaves are dried to arrest the oxidation process.
7. Finally, the leaves are sorted into grades according to their sizes, usually with the use of sieves. The tea could be further sub-graded according to other criteria.