Calibrating your palate
A single cup tasted alone tells you almost nothing, because there is nothing to measure it against. Tasting two things side by side is the fastest way to improve, and it works from the first attempt rather than after years.
What it is
Comparison, done deliberately. Your senses are far better at telling two things apart than at placing one thing on an absolute scale. Nobody can reliably say a tea is a seven for astringency in isolation, and almost everybody can say which of two cups is more astringent. Side-by-side tasting converts an absolute judgement you cannot make into a relative one you can.
How to do it
Brew two teas identically: same weight, same water, same vessel, same time. Any difference in method contaminates the comparison. Taste A, then B, then A again, because the second pass at A is where most of the information appears. Start with pairs that differ in one obvious way, the same tea brewed at two temperatures, or a shaded and an unshaded Japanese green. Once the obvious pairs are easy, narrow the gap.
What to look for
The axis that moved. In a well-designed pair only one or two should, and naming which is the exercise. Deliberately brewing one cup badly is the fastest calibration there is: brew the same leaf at eighty and at a full boil and taste them together, and bitterness and astringency separate themselves in a way no amount of reading will do.
What people get wrong
Tasting too many at once. By the fourth or fifth cup your mouth has accumulated astringency and everything after that reads rough. Three is a sensible limit for one sitting, and plain water between them helps less than most people assume. The other mistake is comparing against a memory. Memory of aroma is unreliable within minutes, let alone across a week, and a comparison against last Tuesday's cup is a comparison against a story you told yourself about it.
