There is an ISO standard for making a cup of tea.

ISO wrote the standard for the shipping container. It also wrote one for making a pot of tea.

In October 1946, 65 delegates from 25 countries met in London to work out how the world was going to agree on things now the war was over. What came out of it was the International Organization for Standardization, which started operating in February 1947.

They hit a problem immediately. In English the acronym would be IOS. In French it would be OIN. So they went with ISO, from the Greek isos, meaning equal, so it would come out the same in every language. The first thing the standards body ever standardised was its own name.

It has published over 25,000 standards since, across more than 800 technical committees, and the whole thing is boring on purpose. The very first committee they set up, TC 1, was screw threads. ISO 668 is why a steel box loaded in Shenzhen fits the ship at one end and the lorry at the other, which is more or less why globalisation happened. ISO 8601 is why the date on your bank statement isn't ambiguous. ISO 216 is why A4 is A4. ISO 3166 is why your country gets two letters.

And then, filed in among all that, there is ISO 3103, which is how to make a cup of tea.

I assumed someone had made this up. They had not, so I started reading into the lore of brew making, and the lore of brew making is absolutely wild.

It didn't reach us from Geneva. We sent it there. It started in 1980 as BS 6008 at the British Standards Institution, went to ISO, and came back as an international standard for everyone else to observe, which is historically how we have tended to operate. It sits under Technical Committee 34, which is food products, and beneath that under Sub-Committee 8, which is tea. There is a tea sub-committee. It meets. Somebody has it in their calendar. Britain holds the secretariat, obviously, jointly with China, which when you think about it for a second is the only pairing it was ever going to be.

It is not called How To Make A Cup Of Tea. It is called Preparation of liquor for use in sensory tests.

They call the tea the liquor. Not the tea. The liquor. There is no alcohol anywhere near it and nobody in the industry appears to think this is worth mentioning. The wet leaf left behind in the pot, meanwhile, is called the infusion, which is the word I would have used for the drink. The entire vocabulary is inside out.

A document about tea that never once says the words "cup of tea" was trying to tell me something, and I read straight past it.

Here is what it says.

Two grams of leaf per hundred millilitres of water, tolerance of two percent. A pot of white porcelain or glazed earthenware, filled to within a few millimetres of the brim. Six minutes. Pour the liquor into a white bowl and tip the wet leaf out onto the underside of the lid so you can have a look at it.

If milk is involved, five millilitres for the large bowl, two and a half for the small one, and it goes in after the tea rather than before. I am aware of what I have just started.

There is an annex describing two pots in widespread use, at 310 and 150 millilitres, with matching bowls at 380 and 200. It contains engineering drawings of their cross sections. Somebody drew a technical elevation of a teapot, and then somebody else checked it, and then a committee approved it.

There is a clause about your water. It has to be about as hard as the tap water wherever the tea is eventually going to be drunk, and if you can't get hold of comparable water you're allowed to use distilled, but the document warns you in writing that your results will no longer bear a true relation to how the tea actually tastes.

In 1999 the British Standards Institution won an Ig Nobel Prize for Literature for it. The Ig Nobels are given for work that first makes you laugh and then makes you think. Everybody stopped at the first bit.

It was revised in 2019. At some point in the late 2010s a room of grown adults sat down and agreed the tea standard wasn't quite right yet. It is still in force.

It is also not for drinking.

The standard says so about itself, in the flat institutional voice of a document with no interest in being interesting. It isn't there to tell you how to brew tea for general consumption. It is there so that meaningful sensory comparison can be made.

Which is where the ridiculous bits stop being ridiculous.

Tea is an agricultural crop. It's subject to rainfall, soil, altitude, and how the weather happened to go that year. No two harvests give you the same leaf and no estate gives you the same thing twice. But the box in your cupboard has to taste identical every time, forever, or you'd clock it on the first mouthful and quietly start buying something else.

Nothing closes that gap except people.

Twinings master blenders taste up to 400 cups a day, sorting each one against 95 descriptors covering colour, viscosity, strength and character. It takes between nine and twelve years to train one, which makes a tea taster slower to produce than a surgeon. Lipton has 79 of them spread across 15 countries, getting through something like a million cups a year between them. A working taster elsewhere in the trade might put away anywhere from 200 to 1,000 teas in a day. A single blend can be built from twenty components from different countries, and the recipe is adjusted continuously so the thing you taste never moves.

Around three quarters of the world's tea exports are sold at auction and they're sold on taste. Price bands are set by tasting. A man slurps it, rolls it round his mouth, spits it into a bucket and puts a number on it, and then a great deal of money changes hands. None of that is a figure of speech. There is an actual bucket.

Which means the taster is the measuring device, and a measuring device that hasn't been calibrated is just a bloke with an opinion. If the brewing wobbles then the difference you're detecting between two teas isn't in the leaf, it's in the pot, and somebody has just paid several hundred thousand pounds for a variable he introduced himself.

So all of it is load-bearing. Six minutes, because five and seven are different teas. The dimensions of the pot, because thermal mass isn't a rounding error. The white porcelain, because a coloured bowl will lie to you about the colour of the liquor. The water hardness matched to wherever the stuff is actually going to be sold, because a tea that tastes right in a lab in Hampshire and wrong in a kitchen in Stockport has failed at the only job it had.

It was never a recipe. It's a calibration procedure you run on a human tongue.

There is one more thing. International standards get agreed by member bodies voting on them, and in the front matter of ISO 3103 there is a line recording that one member body expressed disapproval of the document on technical grounds.

That member body was Ireland.

Ireland is the only country on earth to have formally objected to the international standard for tea, and it did so on technical grounds, which means somebody in Dublin read the whole thing, weighed up the pot dimensions and the six minutes and the five millilitres of milk and the hardness of the water, and decided it was wrong.

They have never said what was wrong with it. As far as I can find, the grounds have never been published anywhere. The objection is recorded, and then left there, and every printing since 1980 has carried it. Everyone has a theory. Mine involves the milk.

So somebody in Dublin read all of it in 1980, got to the end, and voted no. Forty-six years on, the objection is still sat at the front of the document with no explanation attached, and every teabag in your cupboard was signed off by a man with a bucket, brewing it the way the Irish said was wrong.