The behavior of sinking tea leaves is quite telling; it can provide a rough indication of the quality of the tea, though this is not always definitive.
If the Water temperature for brewing Green Tea is high, the tea will Sink quickly; if the water temperature is low, the tea will sink slowly.
The reason is simple: higher water temperatures make it easier for the tea to unfurl, meaning it can expand quickly. When the tea fully integrates with the water, it sinks.
When the water temperature is low, the tea has not fully expanded and is still dry and not sufficiently wet, so it sinks slowly.
Aside from water temperature, there could be inherent reasons as well. If the tea quality is poor, with fewer internal substances, it will be lighter and thinner, causing it to sink more slowly.
Consider tea made from the first spring harvest using plump buds, which would be rich in internal substances, heavy, and substantial, and thus would sink quickly.
It's also possible that the brewing method is incorrect, where the tea was not fully submerged at the beginning, leaving some floating on top and not touching the water, causing it to sink slowly.
Tea that sinks slowly may also be related to the shape and form of the leaves, such as those that are tightly bound or thick, which tend to sink quickly.
Leaves that are flatter and less absorbent will sink more slowly.
In short, tea leaves sink to the bottom because they absorb a lot of water and are inherently heavy.
Under the same water temperature, tea that sinks quickly likely absorbs water well and is heavier. Conversely, tea that sinks slowly likely does not absorb water well and is lighter.
Regardless of weight or quality, all tea leaves will eventually sink to the bottom over time. What we should cherish is the elegant sight of the tea leaves floating up and down in the Cup, which can be missed if not appreciated.