The physics of a nice cup of tea
DOI: 10.1063/PT.5.010064
Sixty-four years ago George Orwell, the author of Homage to Catalonia, Animal Farm, and Nineteen Eighty-Four, wrote an instructional essay for London’s Evening Standard entitled “A Nice Cup of Tea.”
To justify why anyone, let alone a famous writer, should bother to prescribe how to make tea, Orwell began by pointing out that
If you look up ‘tea’ in the first cookery book that comes to hand you will probably find that it is unmentioned; or at most you will find a few lines of sketchy instructions which give no ruling on several of the most important points.
This is curious, not only because tea is one of the main stays of civilization in this country, as well as in Eire, Australia and New Zealand, but because the best manner of making it is the subject of violent disputes.
Then, in dogmatic tones almost free of irony or humor, Orwell enumerated the 11 rules for good tea making, “every one of which I regard as golden.”
Some of those rules are a matter of personal taste. Unlike Orwell, I don’t disdain tea from China. Having lived in Japan and visited China, I enjoy those countries’ red, white, green, and black teas. I do, however, agree with him that tea made with cream, rather than milk, tastes sickly.
But other rules are a matter of physics and chemistry. The black Indian and Sri Lankan teas that Orwell favored are best brewed in water that’s just below the boiling point. The goal, as the Wikipedia entry on tea puts it, is “to extract the large, complex, flavorful phenolic molecules found in fermented tea.”
Orwell rightly advocates promptly using just-boiled water poured into a pre-warmed pot. But I don’t see why the teapot is best warmed on the stove, rather than with boiling water. Heat is heat. While it’s true that briefly swilling out a teapot with hot water won’t transfer much heat, filling the pot with hot water and letting it sit for a minute will.
He’s right, too, to promote the release of flavor from the tea by stirring the pot. Diffusion is a slow process. Stirring a hot liquid, or what a physicist might call convective advection, speeds things up considerably.
Dwelling too much on the science of tea detracts from enjoying it and recognizing its universal, eternal charms. Forty years before Orwell’s essay appeared, Okakura Kakuzo wrote in The Book of Tea,
The world is groping in the shadow of egotism and vulgarity. Knowledge is bought through a bad conscience, benevolence practiced for the sake of utility. The East and the West, like two dragons tossed in a sea of ferment, in vain strive to regain the jewel of life. . . . Meanwhile, let us have a sip of tea. The afternoon glow is brightening the bamboos, the fountains are bubbling with delight, the soughing of the pines is heard in our kettle. Let us dream of evanescence, and linger in the beautiful foolishness of things.
Thanks to tea drinkers Paul Guinnessy and Jenny Stout for drawing my attention to Orwell’s essay.
