CTC black tea
The orthodox route with one slot filled by a different machine, and every other decision in the route reorganised around what that machine needs.
What makes this route what it is
One slot changed and four upstream decisions changed with it. That is the useful lesson: a processing route is not a list of independent choices, and substituting a machine in the middle of it propagates backwards to the field as well as forwards to the cup.
The route, in order
Each note describes what the step is doing in this route. The same operation does a different job in a different chain.
The route tolerates the mixed intake a harvester delivers, because comprehensive maceration downstream evens out material a fine-leaf process could not use.
Taken further than for orthodox manufacture. The rollers need leaf tough enough not to smear, and the wither figure here is a machine requirement rather than a style choice.
A pre-maceration stage that feeds the CTC rollers a continuous, evenly broken stream. Rarely mentioned in descriptions of the route and almost always present in the factory.
Some lines run leaf straight into the rollers, which raises throughput and widens the particle-size spread of the output.
The substituted slot. Counter-rotating toothed cylinders cut the leaf into uniform granules, maximising surface area and setting both the oxidation rate and the eventual extraction rate in one operation.
Much faster than orthodox oxidation because the leaf is comprehensively ruptured, and usually run on a continuous belt where residence time is set by belt speed rather than by judgement.
- 6.
Drying
Fluid-bed driers are standard. The granule dries fast and evenly, which is one of the few places where the route is genuinely easier than the orthodox one.
Output splits into BP, PF, PD and Dust classes. These are particle sizes and therefore extraction speeds, and they carry no information about the garden or the season.
Where the route ends up commercially. Almost all of this tea reaches a drinker as part of a blend built to a fixed profile from lots that change weekly.
How it differs from its neighbours
A route described on its own teaches very little. The useful fact is always which other route it is nearly identical to, and where it leaves it.
One position in the route is filled by a different named method. The shape of the route is unchanged.
The rolling slot, filled by a cutting machine instead of a twisting one. Everything downstream follows automatically and everything upstream had to be changed to suit it, which is why the two routes look similar on paper and produce teas with almost nothing in common.
Where it goes wrong
An under-withered intake smears rather than granulating, producing a sticky mass that oxidises unevenly and dries into hard flakes. Over-withered leaf shatters into dust and the yield of usable grades collapses. The window is narrower than the orthodox one, which is the hidden cost of a route usually described as the forgiving option.
In full
CTC is the dominant manufacturing route in the world by volume and it is, structurally, orthodox manufacture with the rolling table replaced. Withered leaf is fed through pairs of toothed cylinders turning at different speeds, which crush, tear and curl it into hard granules of consistent size. Because the leaf is comprehensively ruptured rather than twisted, oxidation runs fast and evenly, and the finished granule gives up almost everything it has in the first two or three minutes in the cup. What is worth noticing is how far back the consequences reach: the wither has to be harder, because leaf that is still turgid smears in the rollers instead of granulating; a rotorvane pre-maceration is usually added ahead of them to feed the machine an even stream; and the harvesting can be mechanical because the route is far more tolerant of a mixed intake than any fine-leaf process. One substitution, and the whole route reorganises around it.