Many tea lovers and chajin get into the processing of tea. They want to know all the differences in how one type of tea is processed versus another type. While this is not actually necessary for the enjoyment of tea (and can even be an impediment to it!), knowing some basics about tea processing can be an interesting way to learn more about one's beloved beverage.

That said, unless you've seen tea processing firsthand, a lot of this "tea processing" information is just jargon.


Sure, you might learn that withering is used in black tea production and oolong tea production, as well as in white tea production, shou puerh production and some (although not much!) in green tea and yellow tea production. But what IS withering, exactly?

Most tea sites and tea books will tell you that withering is a process in which excess water content is removed from tealeaves. They usually name a certain percentage of water loss and a certain length of time. Before I started visiting tea processing factories around the world, I told people the same thing.

But here's what's really interesting about withering... it's not so scientific and exact, and if you ask tea processors they will often tell you that they never use metrics like this and that these figures are pretty much made up, or they'll give you such widely varying figures that (when you ask people from different tea origins making different types of tea) you eventually realize that there is no way to present an honest "it takes this many to that many hours" kind of statement without it being an absurdly big range (like one to 36).

But this isn't because withering is complex! When you get down to it, withering is really very simple, and not so scientific at all.

After tealeaves are plucked, they're laid out on a surface that will give them some air flow (usually woven bamboo trays / mats or a long trough with perforated material in the base and strong fans that pull moist air down and away from the leaves). The leaves naturally wilt, just like lettuce does when it's left out in the heat.* The leaves have more moisture than the air, and equilibrium starts to take hold. Heat or especially dry air can make it happen faster, and so can good air flow.

Most tea processors (whether they're in a big factory or a small mom-and-pop operation) have some very special scientific instruments to tell when the leaves are done withering: their eyes and hands! Appearance and feel are essential to this process, and many of the tea makers I asked also told me that instinct are experience are both key to knowing when a tea is done withering. From the appearance of the leaves, they can see how much the leaves have shrunken down as a result of water loss. From the feeling of the leaves, they can see if the leaves have lost enough moisture to be soft and pliable enough for the next step in processing (which is often rolling). And from instinct and experience, the good ones can add that certain finesse that makes their tea so great.

When a tea processor is confident that the leaves are done withering (which is to say that they have reduced in size enough and are soft and pliable enough for the next step), then they remove the tealeaves from the withering area and move on to the next step. They usually use their hands or a pitchfork-like instrument to do this.

There are a few problems that factories can run into during withering. A common one is to pile up the tea too high. This creates uneven withering, and can encourage the leaves to start fermenting inside the pile. Another is high humidity, which can drastically slow the withering process. And a third is unsanitary facilities, which can encourage bacterial growth during withering (and other stages of processing) and throw off the final flavor of the tea. And older, tougher leaves (and leaves from more "leathery" tea varietals... and leaves that have been rained on recently) can take much longer to wither than young buds (and thin-leaved teas... and dry leaves). (Note: A longer withering step is called a 'hard wither' in some places.) But aside from these pitfalls, the basic premise of withering is remarkably simple:

1. Lay out some tealeaves.
2. Let them do their thing.
3. Stop them when they're done.

When it's worded this way, it can really shift your perspective on tea processing. Is making tea really all about scientific parameters? Or is it about an ancient tradition of picking and working with plant materials, listening to them as you go? It depends on what you love about tea and why you want someone to make it... I'm simply offering an alternative perspective to the scientific one so often discussed.

* Do you REALLY want the science on this? OK. Many plants' cells (including tealeaves' cells) look a bit like little bricks. When they have plenty of water in them, they look swollen, more like lozenges, and the plant material feels nice and crisp. When they lose water, they deflate and the plant material softens and shrinks down. Think of a fresh carrot versus a wilted one, or fresh ginger versus drying ginger.