Fine green teas are the least forgiving of all teas to make to perfection. In making such for guests, you must learn to use a single guywan that can be drained at the proper instant into a small pitcher. The thumb goes atop the lid and the fingers support the saucer. You tilt the lid so that it holds back the leaf while you pour off the liquor. Use the pitcher to fill thimble cups. With less exalted green teas, water temperature matters much less. Besides, each person can drink from his own guywan and serving guests is just a matter of replenishing each guywan with hot water as required.
When you prepare black tea, oolong, or Pu-Er in a guywan, you begin by rinsing the leaves. That is, the first water you pour on—well under half the guywan—is immediately drained off and discarded. (Remember that the cup is never removed from the saucer.) You now bring the guywan to your nose and uncover it, breathing in the freshly released aroma of the leaf. Only now that you have inhaled its perfume is water poured on again, to steep. With white or green teas you omit rinsing the leaves and you steep the tea without replacing the lid, to encourage cooling. Pour just a few drops of water on green leaf to release its aroma for you to inhale before infusing. With black, oolong, or Pu-Er teas, I like to use just-boiling water, then cover the cup and allow considerably longer steeping time. These teas are not only less beautiful to watch infuse, but they also taste better hotter. Black tea should almost always be decanted to prevent over-steeping.
A note on spelling:
It's entirely my fault that the name is also spelled "gaiwan." Apparently I became the first round-eye to anglicize the Chinese name for this vessel when I was composing the first in-house menu for the first traditional Chinese tea house in America, Imperial Tea Court, which opened in San Francisco during the summer of 1993. When I saw "gaiwan" in cold print, however, I had second thoughts and opted for "guywan" as preferable spelling. It was too late, alas, and the schism dates from this first need for the term in English.