Blocking the venting hole may be the most popular method of testing a zisha teapot, however, the airtightness of a teapot may not be the most important factor in selecting our teapot.
In the art of preparing Chinese tea, we do not purposefully block the flow of water by covering the air vent. The blocking of the vent and the halt of the flow would create a sudden and disruptive impact to the whole process. The entire process of preparing tea should be smooth and display a feeling of serenity. Timing should not be controlled this way.
Then why do we use this test? It tries to measure the level of craftsmanship--particularily the tightness and tolerance of the teapot. However, in todays production environment where machinery can be used to aid in manufacture of teapots, the tolerances can easily be very high, but without much craftsmanship at all. The most important impact is that the clay used in wholly machine-manufactured teapots are inferior.
So what should we look for in a teapot? Well, as long as our tea does not pour out from under the lid before it even comes out of the spout, we should consider a few other things.
As many people have mentioned, ergonomics are definitely at the top of the list. Balance in an instrument creates comfort and useability. Front, or spout heavy teapots cause strain on the wrist. Other issues of alignment and basic design help with ergonomics and are generally common sense, so I won't drag on here.
The most important factor is the quality of the clay. The pureness of the zisha clay and the proper firing of the clay at adequate temperatures is what directly affects the flavor of your infusion. The airtightness and ergonomics can affect your brewing technique, and subsequently affect your tea. The clay's direct contact with tea, directly affects the outcome of your brew.
How do you look for good clay? That's another article. Let me know if you want to read more.
Bill
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