Process — Two methods of manufacturing black tea

The diagram illustrates two alternative methods by which black tea is manufactured, an orthodox process producing whole-leaf tea and a CTC process producing tea for teabags.

Overall, both methods consist of six stages and share the same basic sequence, from harvesting through to packing. The crucial difference lies in how the leaves are broken up and how quickly they are processed, which is what determines the final product.

The two processes are identical up to a point. In each case fresh leaves are first harvested and then withered, a stage in which warm air draws moisture out of them. Later, both batches are oxidised in a humid environment until the leaf darkens, after which hot air halts oxidation and dries the tea ready for packing.

The crucial difference occurs at the third stage. In the orthodox method the leaves are rolled while still whole, so that they release their juices without breaking apart, and they are then oxidised slowly over two to three hours before being graded by leaf size. In the CTC process, by contrast, the leaves are shredded by toothed rollers, and oxidation is cut short to roughly an hour, producing small granules that are sifted directly into teabags rather than sorted by size.