Beer, a complete course

Class P3.1

Date codes, and which beers die fastest

Two kinds of date, four formats, and the order in which beers give up. Age damages every beer, but a hazy IPA and an imperial stout are on completely different clocks.

By the end of this class you will be able to

Find the date on a can, a bottle or a carton, and read all four common formats
Turn a best before date into the age of the beer in front of you
Say which families need drinking in weeks, which in months, and which in years

P3.1.1 Finding the date, and reading it

Two kinds of date that mean different things, and the four ways breweries print them.

A beer can carry two completely different kinds of date, and they are not interchangeable. Packaged on is a fact: this beer went into this container on this day. Best before is a judgement: the brewery decided how long it wanted this beer sold for.

Nothing in United States law requires either one. Freshness dating on beer is voluntary, so what you find on the can is whatever that brewery chose to tell you. Some tell you everything, some tell you almost nothing.

Packaged on is the more useful of the two, because it gives you the number you actually want. That number is the age of the beer, and every judgement on the next screen is made from it.

Where the code hides

Cans. On the bottom, or stamped around the rim of the lid. Turn the can over first, every time.
Bottles. On the shoulder or the neck in small ink characters, or printed on the back label near the barcode. On brown glass it can be genuinely hard to see, so tilt it towards a light.
Six packs and cases. On the end of the carton, usually larger and easier to read than the can. If the shop has a case open, look there first.
Draught. Not printed anywhere you can see. That one is a question rather than a search, and the words are further down this screen.

The four formats you will meet

The last row is the one that catches Americans out. Most of the world writes the day first.
What it looks like	What it is	How to read it
CANNED ON 06 03 26	A packaged on date, month first	Subtract it from today. That gives you the age of the beer, which is the number every decision is made from.
BEST BY 09 01 26	A best before date, month first	Work backwards. Subtract the window that brewery allows for that style, and you have roughly the packaging date.
26154	A Julian date. Year, then the day of the year	Day 154 of 2026 is 3 June. To read one quickly, divide the day number by 30 and you have the month, near enough.
Mindestens haltbar bis 03.06.26	A German or Belgian best before date, day first	Day, month, year. That reads 3 June 2026, not 6 March. The German phrase just means best before.

Worked example: Reading a can in the shop

You are holding a 16 ounce can of hazy IPA. The bottom of the can reads L26154 09:42. Today is 20 June 2026.

Ignore the letter and the time. L marks the filling line and 09:42 is the minute the machine filled that can. Neither helps you.
Split what is left. 26 is the year. 154 is the day of that year.
Convert 154. Divide by 30 and you get about five, so you are somewhere in the fifth or sixth month. Counted properly, day 154 of 2026 is 3 June.
Subtract. Today is 20 June, so the beer was canned 17 days ago.

Seventeen days for a hazy IPA is good. Thirty is the edge. Sixty and you are drinking something the brewery would not want its name on.

Turning a best before date into an age

A best before date is a deadline, and a deadline on its own tells you nothing about age. To get the age, subtract the window that brewery allows for that kind of beer.

These are the common windows, not rules. A brewery can pick any number it likes.
Family	Window usually allowed	So a best before date in September means
American IPA and pale ale	90 days	It was packaged around June
German and Czech lager	6 to 9 months	It was packaged between December and March
Belgian abbey and strong bottle conditioned ale	2 to 3 years	It was packaged two or three years ago, which is fine for these
Imperial stout, barleywine, strong dark beer	1 to 5 years, when dated at all	Very little. The date is doing almost no work on a beer like this

The four questions that get you a straight answer

All four are short, none of them accuses anybody of anything, and staff who know their stock enjoy being asked.

In a shop: "Do you know when this came in?"
In a shop, better: "Which of your IPAs is the freshest right now?"
If the can is unreadable: "Is there a date on the case?"
At a bar: "How long has that keg been on?"

The second one is the strongest, because it asks the shop to do the work and it gives them something to be proud of. A good bottle shop will walk you to the cooler. A shop that cannot answer has told you something too.

A code you cannot read is still information

Some beers carry only an internal lot code that means something to the brewery and nothing to you. That is a choice somebody made. Breweries that are proud of their freshness print a date you can read, in large characters, on the part of the can you are looking at.

When two cans sit side by side and one of them tells you when it was filled, that is a real reason to pick it.

Covered in Module P2, Faults

What old beer actually tastes like. Wet cardboard for oxidation, and almost nothing at all for a beer that has simply lost its aroma. The ten faults are taught once, in Module P2.

Sources: Brewers Association, Draught Beer Quality Manual, fourth edition 2019 · CraftBeer.com, Craft Beer Retailer Temperature Cheat Sheet, published by the Brewers Association

Check yourself

A can says BEST BY 11 12 26. What have you been told?
Answer: A deadline the brewery chose, which you have to work backwards from to get the age
A best before date is a commercial judgement about how long the brewery wants the beer sold, so the age is hidden inside it. Reading it as a packaging date is the tempting mistake, and it makes a fresh beer look ancient and an old one look new. Beer does not become unsafe, which is the third answer and is wrong for a different reason.
A can is stamped 26154. Which month was it filled in?
Answer: june
June. The first two digits are the year and 154 is the day of that year, which lands on 3 June. The quick version is to divide the day number by 30, which gives about five and puts you in the fifth or sixth month. That is close enough to decide whether to buy the can.
United States law requires breweries to print a freshness date on beer.
Answer: False
False, and this is why the formats are such a mess. Freshness dating on beer is entirely voluntary here, so each brewery picks its own format, its own wording and its own hiding place. It also means that a brewery which prints a clear, large, readable date has chosen to, and that choice usually goes with the rest of how they treat the beer.
Before you read on. When an American brewery puts a best before date on an ordinary IPA, how many days after packaging does it usually fall?
Answer: 90days. Think about how long a six pack sits in a shop before somebody buys it, and how long the brewery would want its name on that beer.
Ninety days is the common industry setting, and some breweries deliberately go much tighter. People usually guess higher, because a year feels like a normal shelf life for something in a supermarket. Beer is not that kind of product. Ninety days is a commercial compromise between freshness and how long a shop can be expected to hold stock.
Pair each printed code with what it is telling you.
Answer: CANNED ON 06 03 26 with A fact: the day it went into the can · BEST BY 09 01 26 with A judgement: the last day the brewery wants it sold · 26154 with A day of the year, with the year in front · Mindestens haltbar bis 03.06.26 with A best before date written day first, as most of the world writes them
Two facts and two judgements, in two orders. The Julian code catches people because it looks like a batch number, and the German one catches people because 03.06 reads as March to an American eye. Getting the day and month the wrong way round moves a date by up to eleven months, which is the largest single error you can make on a shelf.
Put the steps in order for working out how old a beer is from a best before date.
Answer: 1. Read the date, and check whether the day or the month comes first 2. Work out which family the beer belongs to 3. Subtract the window that family usually gets, to find roughly when it was packaged 4. Subtract that from today to get the age
Read, classify, subtract the window, then subtract again. The step people skip is the second one, and it carries all the meaning. A 90 day window for an IPA and a three year window for a Belgian abbey ale turn the same printed date into beers of completely different ages.
Where should you look first for a date on a six pack of cans?
Answer: The end of the carton, which is usually printed larger than the can
The carton end, because it is printed for a warehouse to read at a distance and is far easier on the eyes than tiny ink on an aluminium base. Failing that, the bottom of the can or the rim of the lid. Nothing useful is printed on the tab, and cans have no back label, which is exactly why the code has to go somewhere awkward.
You are choosing between two cans of the same IPA. Which of these are real reasons to pick one over the other?
Answer: One is canned nine days ago and the other twenty six days ago · One was in the cooler and the other on a warm shelf · One carton is dusty and pushed to the back of the shelf
Age, temperature and how long it has clearly been sitting there are the three things that damage beer on a shelf, and all three are visible before you pay. A dent is the tempting fourth. Unless the seam is damaged, a dented can is sealed and the beer inside is untouched, which is one of the reasons cans travel so well.
A best before date printed as 03.06.26 on a German bottle means 6 March 2026.
Answer: False
False. It means 3 June 2026. Germany, Belgium, Britain and most of the world write the day first, and American labels write the month first. On an imported bottle, assume day first unless the number is above twelve and settles it for you. Reading it the American way can make a nine month old beer look three months old.
You are at a bar and want to know how fresh the IPA on tap is. What do you say?
Answer: "How long has that keg been on?"
How long has it been on. It is a factual question about something the bar actually knows, and the answer is usually immediate. Asking whether a beer is fresh invites the answer yes, because nobody says otherwise. Asking for a keg date code asks for something the person pouring almost certainly cannot see.

P3.1.2 Which beers die fastest

The queue, from weeks to years, and why the beers people treat most casually are the ones with the least time.

Age damages every beer, but not at the same speed. Two things decide how long a beer has: what it has to lose, and what it has to hide behind.

What it has to lose is aroma. Hop aroma is the most fragile thing in beer, and it starts leaving on the day the beer is packaged. What it has to hide behind is strength, dark malt and sweetness, which cover up the flavours that age brings in.

Put those together and you get a queue. At the front, with the least time, sits the beer with the most aroma and the least cover.

Top of the table, weeks. Bottom of the table, years. The gap between the two ends is about a hundredfold.
Beer	What goes first	Drink it within	How it reads when it is late
Hazy IPA	The fruit aroma, which is most of what you paid for	30 days, cold the whole way	Dull and flat, with a faint cardboard note. Nothing arrives to replace the fruit
Any pale hoppy beer: IPA, pale ale, session IPA	Hop aroma first, then the bitterness	90 days	Sweeter, softer, rounder, and smelling of very little
Non-alcoholic beer	Everything, quickly	Buy the newest date in the shop	Cardboard and raw grain, and both turn up early
Pale lager and Pilsner	The clean bready malt, then the delicate hop	3 to 6 months	Cooked sweetcorn, cardboard, stale honey. It has nowhere to hide
Wheat beer	The banana and clove	3 to 6 months	Bready and blank. The yeast character is the first thing out of the door
Amber, brown, porter, stout	Not much, and slowly	6 to 12 months	A little duller each month, with the roast holding on longest
Imperial stout, barleywine, strong dark Belgian	The hop character, then nothing for years	1 to 5 years, sometimes better later	Dried fruit, sherry and leather, which many people prefer

The beers people baby are the wrong ones

Ask somebody which beer in their fridge is the most delicate and they will point at the expensive imperial stout in the wax dipped bottle. That is the sturdiest thing in the house.

The four dollar can of hazy IPA next to it is the one on a clock. It is also the one that gets left in a hot car, stood on a windowsill, and drunk in August after being bought in May. The care and the fragility point in opposite directions.

What the research actually shows

Two findings are worth carrying around.

Temperature does more damage than time does. The trade rule, published by the Brewers Association, is called 3-30-300. Three days at 90F, which is 32C, costs a beer about as much flavour as thirty days at room temperature. Both cost it about as much as three hundred days in a fridge at 38F, which is 3C. It is a rule of thumb from industry rather than a laboratory result, and it is still the most useful sentence in this class.

The clock starts fast. In a 2019 study, commercially brewed dry hopped beer was given controlled amounts of oxygen. It was then stored either chilled at 3C, which is 37F, or warm at 30C, which is 86F. Storage temperature had the largest effect on how the beer smelled, and a tasting panel could pick out the oxygen differences after only two weeks. The warmer, more oxidised beers had lost tropical, citrus and hoppy character and picked up malty, dried fruit and cardboard notes.

Neither finding says a beer falls off a cliff on a particular day. They say the same thing in two ways. The damage is continuous, and cold slows it down enormously.

The cold chain

A cold chain means the beer was kept refrigerated from the brewery to the shelf, with no warm stretch in a lorry, a warehouse or a shop. Some breweries ship their hoppy beer this way and ask shops to keep it in the cooler.

You can usually see whether a shop is playing along. If the same beer is stacked both in the cooler and on a warm shelf by the door, buy the cold one. It is the same beer with a different history.

Once a hoppy beer is yours, keep it cold and drink it. Warming it up once on the way home is not a sin. Sitting at room temperature for six weeks is, and the 3-30-300 rule says roughly how much it costs you.

Two things people say that are wrong

Best before is not a use by date. Beer does not become unsafe. Alcohol, hop compounds and the low acidity between them make beer a hostile place for anything that could hurt you, which is most of the reason people drank it for centuries. An out of date beer is disappointing, not dangerous.

Cans are not the cheap option. A can blocks all light, seals better than a crown cap, and chills faster. For hoppy beer it is the better package, and the best breweries in the country moved to cans for exactly that reason.

Worth remembering

Hazy thirty, hoppy ninety, pale lager a season, big and dark for years.

Four numbers in the order you meet them. Thirty days for a hazy IPA, ninety for an ordinary IPA or pale ale, three to six months for a pale lager or a wheat beer, and years for anything strong and dark. Every other beer in the course sits somewhere between the second and third of those.

Three beers to test this on

Sierra Nevada Hazy Little Thing, canned all year and stocked almost everywhere, with the date on the base of the can. Buy the newest one in the shop and, if you can find one, the oldest. Drinking those side by side teaches this class better than the class does.
Bell's Two Hearted Ale, an IPA sold year round in cans and bottles and dated clearly. It is a single hop beer, so what age takes away from it is easy to name.
Reissdorf Kolsch, imported from Cologne in bottles and 16 ounce cans, carrying a best before date rather than a packaging date. Good practice at working backwards, and a delicate pale beer that shows its age quickly.

Covered in Module 11, Non-alcoholic and low alcohol

Why non-alcoholic beer is at the front of the queue. Alcohol is a preservative. Take it out and the beer has less protection, which is why these cans need the newest date on the shelf.

Sources: Barnette and Shellhammer, Evaluating the Impact of Dissolved Oxygen and Aging on Dry-Hopped Aroma Stability in Beer, Journal of the American Society of Brewing Chemists, 2019 · Jaskula-Goiris and others, Influence of transport and storage conditions on beer quality and flavour stability, Journal of the Institute of Brewing, 2018 · CraftBeer.com, Craft Beer Retailer Temperature Cheat Sheet, source of the 3-30-300 rule · Saison and others, Contribution of staling compounds to the aged flavour of lager beer, Food Chemistry, 2009

Check yourself

Sort each beer into how long it has before age becomes the main thing you notice.
Answer: Hazy IPA goes in Weeks · Non-alcoholic pale ale goes in Weeks · German Pils goes in Months · Hefeweizen goes in Months · Imperial stout goes in Years · English barleywine goes in Years
Aroma at the top, cover at the bottom. A hazy IPA is almost entirely fragile aroma, and a non-alcoholic beer has no alcohol protecting it. A Pils and a Hefeweizen have delicate character but a little more structure. The strong dark beers have so much malt, sweetness and alcohol that the changes of a year barely register, and are sometimes welcome.
Why does a hoppy beer suffer from age more than a stout of the same strength?
Answer: Its aroma is the point of the beer, and aroma is the first thing to leave
What you paid for is the part that goes first. Hop aroma compounds are volatile and they fade from the day of packaging, so a beer built entirely on them has the most to lose. Hops actually preserve beer rather than destabilise it, which is the tempting wrong answer, and pasteurisation is a choice unrelated to style.
Before you read on. Beer stored three days in a hot car at 90F loses about as much flavour as beer kept at ordinary room temperature for how many days?
Answer: 30days. Think about how much faster food goes off on a warm worktop than in a fridge, then apply the same instinct to a can.
Thirty days, under a trade rule of thumb called 3-30-300: three days at 90F, thirty days at room temperature and three hundred days in a fridge do about the same damage. Most people guess a week, because three days in a car does not feel like a month of anything. Heat is the fastest way to ruin beer that does not involve sunlight.
Click the part of the colour scale where beers are hurt most by a warm month on a shelf.
Answer: Straw to gold, 2 to 4 SRM
The palest band. A pale beer has no dark malt, no heavy sweetness and usually little alcohol, so anything age brings in arrives with nothing on top of it. The same month in a black beer is largely hidden by roast and sugar. This is the same reason faults show up first in pale lager.
A beer past its best before date can make you ill.
Answer: False
False. Beer does not become unsafe with age, it becomes less good. Alcohol, hop compounds and low acidity make it a hostile place for anything harmful, which is a large part of why people drank beer instead of water for centuries. What you get from an old beer is cardboard and disappointment, not danger.
Which of these beers should you buy on the day you plan to drink it, rather than stocking up?
Answer: A hazy IPA · A non-alcoholic lager · A German Pils
The first three are all racing a clock, for slightly different reasons: aroma, missing alcohol, and having nothing to hide behind. The imperial stout is the one beer here you can genuinely forget about for a year, which is the opposite of how most people treat their fridges.
Pair each beer with what age takes away from it first.
Answer: Hazy IPA with The tropical fruit aroma · Hefeweizen with The banana and clove from the yeast · Pilsner with The clean bready malt and the delicate hop · Imperial stout with The hop character, and then very little for years
Each style loses its most fragile part first, and that part is usually the reason people order it. The stout is the odd one out: it loses its hop character early too, and almost nobody notices, because the hops were never what the beer was about.
Which single purchase would teach you the most about what age does to hoppy beer?
Answer: Two cans of Sierra Nevada Hazy Little Thing, the newest and the oldest the shop has
The same beer at two ages. Everything else is held still, so the only difference you can taste is time, and the comparison is unmistakable. A single fresh can gives you nothing to compare against, and a mixed six pack changes so many things at once that you learn about breweries rather than about age.
How many days does a hazy IPA really have before it stops being the beer it was? Type the number.
Answer: 30
About thirty days, kept cold throughout. Ninety is the answer for an ordinary IPA or pale ale, and the two get confused constantly because both are called IPA. The hazy is the more fragile of the two, because more of what you paid for is aroma and less of it is bitterness.
The same beer sold from the cooler and from a warm shelf is the same product.
Answer: False
False, and this is the most useful thing on the screen when you are actually standing in a shop. Two cans with identical dates can have had completely different lives, and warmth is the thing doing the damage. Where a shop keeps its hoppy beer tells you both how that beer is now and how seriously the shop takes its stock.

Class P3.1 done

You can find a date on any package, read all four formats, turn a deadline into an age, and say which beers are on a clock and which are not.

The three lines worth keeping

Hazy thirty, hoppy ninety, pale lager a season, big and dark for years.
Packaged on is a fact. Best before is a judgement. Work out the age either way.
Three days hot, thirty days warm and three hundred days cold do the same damage.

Class P3.2

Cellaring, and which beers improve

A short list, honestly drawn. Most beer gets worse with age, a few get more interesting, and the conditions that matter are cheaper and simpler than the hobby suggests.

By the end of this class you will be able to

Name the families that improve with age and the features that rule a beer out
Keep beer at home properly using a cupboard and a cardboard box
Run the three bottle experiment that settles the question for your own palate

P3.2.1 The short list

What ageing actually does, which beers benefit, and the features that rule a beer out on sight.

Start with the honest headline. Most beer does not improve with age. It fades. The great majority of what is on a shop shelf is at its best on the day it was packaged, and every week after that is a small subtraction.

A small group of beers is different, and the reason is worth understanding, because it explains the whole list.

What ageing does

Oxygen gets into every beer at packaging, in tiny amounts. Over months it reacts with things in the beer and makes new compounds. That process is the same in every beer. What differs is how the result reads.

In a pale, dry, delicate beer the new compounds read as cardboard and stale honey, and there is nothing there to cover them. In a strong dark beer they read as dried fruit, sherry, leather and toffee, sitting on top of malt and sugar that were already pointing that way. Same chemistry, opposite verdict.

Two other things happen at the same time. The hop character fades, which matters less in a beer that was never about hops. And the hard edge of the alcohol softens, which is why a very strong beer can feel rounder after a year even though nothing was added.

What improve means here

It means changed in a direction many people prefer. Plenty of drinkers like a fresh imperial stout better than an aged one, and they are not wrong. Nobody is measuring anything. What is true is that these beers change without breaking, and that is what makes the experiment worth doing.

The list

Six entries. That is the whole list, and everything on it is either strong, dark, or alive in the bottle.
Family	What a year or three does	How long is sensible
Imperial stout	Roast softens, dried fruit and sherry come forward, the hot alcohol edge settles down	1 to 5 years
Barleywine, English or American	Toffee deepens into marmalade and leather. The American ones lose their hops in the first year, which is most of the change	1 to 5 years
Old ale and strong dark Belgian ale	Dried fruit deepens, sweetness drops, and the beer gets drier as the live yeast keeps working	2 to 5 years
Gueuze and lambic	Genuinely evolves, because the wild yeast in the bottle is still alive and slow. The classic example of a beer built to be kept	5 to 20 years
Eisbock and doppelbock	Dark fruit and toffee deepen, and the beer becomes smoother	1 to 3 years
Orval	A special case. The dry hop character fades over the first year while the wild yeast keeps drying the beer out, so it is a different drink every few months	Up to about 5 years

What rules a beer out

Hop aroma is the point of it. Anything you would call hoppy loses the thing you bought within months. That includes every IPA, and it includes the hoppy American barleywines if the hops were why you liked it.
It is pale. Pale beer has nothing to hide behind, so the cardboard arrives naked.
It is under about 7% and has no live yeast in it. Alcohol is both a preservative and a cover. Below that strength, most beers have neither enough alcohol nor enough body to carry the years.
It has fruit added. Fruit aroma fades faster than almost anything else in beer.
It is already old. Age is cumulative, and you cannot start a clock that has been running since last spring.
You did not like it fresh. Keeping a beer does not fix it. Ageing changes a beer, it does not repair one.

Sources disagree

Does strength on its own tell you whether a beer will age well?

Common advice online. Anything above about 8% will improve with time. Strength is the test.
How the styles actually behave. A 9% double IPA is ruined in six months, and a 6.2% Belgian ale with live yeast in it improves for years. Strength is one factor among several.
What the brewers of these beers say. Several breweries print ageing advice on the strong dark bottles and none of them print it on the hoppy ones, at any strength.

Strength helps, and on its own it is a poor test. The reliable version has three parts: strong, dark, and not built on hop aroma. If a beer has live yeast in the bottle as well, that helps again, because the yeast keeps taking up the oxygen. Use all three and you will not go far wrong.

Most cellaring advice is wishful

Keeping bottles feels like expertise, so people do it, and then they talk about the results in a room full of other people who also did it. That is a hard place to say a beer was better last year.

The honest experience of most people who have opened a lot of old bottles is that a minority are improved, a good number are about the same, and a real share are worse. The ones that improved are nearly always on the list above.

Nothing here is a reason not to do it. It is a reason to buy three bottles rather than one, so that you find out instead of guessing.

Bottles that make this easy

Sierra Nevada Bigfoot is released every January with the year printed on it, sold nationally, and cheap enough to buy three. It is also hopped like an IPA, so the first year of change is dramatic and easy to taste.
Fuller's Vintage Ale is bottled once a year with the year on the label and live yeast in the bottle, and is imported into the United States. It is the tidiest way to buy the same beer at two ages.
North Coast Old Rasputin is brewed year round and stocked everywhere, which makes it the easy control: buy two, drink one, keep one.
J.W. Lees Harvest Ale is brewed once a year from that season's malt and hops and is built to be kept. It is the strongest thing on this list and the slowest to change.
Orval is sold in good bottle shops all year with the bottling date on the label, and it changes faster than anything else here. Buy two, six months apart in age, and drink them together.

Covered in Module 6, Porter and stout

Imperial stout, the style this class was built around. The strongest and darkest thing in the course, and the beer most likely to reward a year in a cupboard. Taught once, in Module 6.

Sources: Saison and others, Contribution of staling compounds to the aged flavour of lager beer, Food Chemistry, 2009 · Silva Ferreira, Bodart and Collin, Why Craft Brewers Should Be Advised to Use Bottle Refermentation to Improve Late-Hopped Beer Stability, Beverages, 2019 · Merchant du Vin, Orval Trappist Ale, bottled with live yeast and dated

Check yourself

Why does age make a pale ale taste of cardboard and an imperial stout taste of dried fruit?
Answer: The same reactions happen in both, but the stout has malt and sugar covering the result
One chemistry, two verdicts. Oxidation produces new compounds in every beer, and whether they read as a fault depends entirely on what else is in the glass. Dark malt does not block oxygen, and the seal is the same crown cap on both bottles, which is why the other two answers are tempting and wrong.
Sort each beer by whether keeping it for two years is a reasonable idea.
Answer: Imperial stout goes in Worth keeping · Gueuze goes in Worth keeping · English barleywine goes in Worth keeping · Double IPA at 9% goes in Drink it now · Hefeweizen goes in Drink it now · Non-alcoholic pale ale goes in Drink it now
Strong, dark, and not built on hops for the first bucket. The double IPA is the one people put in the wrong place, because it is stronger than most of the beers on the list. Strength does not save a beer whose whole point is aroma, and at two years it will taste of sweet caramel and very little else.
Which features on a bottle argue against keeping it?
Answer: It is pale · The label leads with the hop varieties · It is 5.2%
Pale, hoppy and modest in strength are the three disqualifiers, and any one of them is enough. Live yeast is the opposite: yeast in the bottle keeps taking up the oxygen that would otherwise be doing the damage, which is part of why so many Belgian bottles hold up for years.
Keeping a beer for a year can fix a beer you did not enjoy.
Answer: False
False, and it is the most expensive mistake in this class. Ageing changes a beer, it does not repair one. A thin beer becomes an old thin beer and a faulty beer becomes an old faulty beer. If you did not like it fresh, the only question worth asking is what to buy instead.
Which beer is the easiest place to start, if you want to taste what a year does?
Answer: Sierra Nevada Bigfoot, which is released every January with the year printed on it
Bigfoot, because it is dated, national, repeated every year and inexpensive enough to buy three. A one off bottle is the tempting answer and it fails on the most important point: when the experiment is over you cannot buy a fresh one to compare against. Repeatability is the whole value.
Pair each beer with what a few years does to it.
Answer: Imperial stout with Roast softens and dried fruit comes forward · American barleywine with The hops disappear in the first year, leaving toffee and marmalade · Gueuze with Keeps evolving, because the wild yeast in the bottle is still working · Orval with Gets drier month by month while the dry hop character fades
Four beers, four different mechanisms. Two are chemistry alone and two involve something alive in the bottle. Orval is the fastest mover of the group, which is why it is such a good beer to buy two of.
Any beer above about 8% will improve with a couple of years in a cupboard.
Answer: False
False, and it is the single most repeated piece of bad advice about keeping beer. A 9% double IPA is a ruin in six months while a 6.2% Belgian ale with live yeast improves for years. The workable test has three parts: strong, dark, and not built on hop aroma.
One word for the gas that gets into a bottle at packaging and does most of the damage over the following year.
Answer: oxygen
Oxygen. Tiny amounts get in when the beer is packaged, and over months they react with compounds in the beer. Carbon dioxide is the tempting answer because it is the gas people associate with beer, and it is the one gas in there that is doing no harm at all.
Which beer style has the longest tradition of being kept deliberately for years?
Answer: Gueuze, which is blended from lambics of different ages and then kept in the bottle
Gueuze. It is blended from young and old lambic and then bottled with live wild yeast, and Belgian producers have sold it as something to lay down for well over a century. Lager was indeed stored cold in caves, but that was part of making it, not a way of keeping a finished bottle for years.
Which of these are honest reasons to be sceptical about cellaring advice you read online?
Answer: People who kept a bottle for three years are not neutral about it · Most reports compare a memory of the fresh beer, not a fresh bottle · The beers that get written about are chosen because they worked
Investment, memory and selection, and all three push the same way. The fourth is not a reason, because old beer is not dangerous at any age. Buying three bottles fixes the first two problems at once, since you get a real comparison instead of a remembered one.

P3.2.2 Conditions, and the three bottle rule

Four conditions that matter, in order, and the cheap experiment that answers the question for you.

Two things that matter a great deal, one that matters some, and one that mostly does not.
Condition	Aim for	Why	How much it matters
Temperature	50F to 55F, which is 10C to 13C	Warmth speeds up every reaction in the bottle. Steady matters more than exact, because a cupboard that swings from 55F to 80F and back is worse than one that sits at 65F	Large
Darkness	A closed box or a dark cupboard	Light strikes hop compounds and makes the skunk smell, and it can do it in an afternoon through clear or green glass	Large
Upright	Standing up, including corked bottles	Sediment settles into a compact layer you can pour around, and the beer stays off the cap. This is the opposite of the advice for wine	Medium
Stillness and humidity	Anywhere that is not a washing machine	Vibration and dry air are talked about constantly and do very little to a crown capped bottle of beer	Small

A fridge at 38F, which is 3C, is a perfectly good place to keep beer. It slows the changes down rather than stopping them, so a beer kept there ages more slowly than one at 55F. It will not come to harm, and it is far better than a warm kitchen.

The place to avoid is the one most people use. A kitchen cupboard next to the oven, a garage, or a shelf above the fridge will spend half the year above 75F, which is 24C. At those temperatures a year does the work of several.

Places that already exist in your home

A cupboard or wardrobe against an interior wall, on the ground floor or lower. Interior walls swing less than exterior ones.
A basement, which is usually the closest thing to a real cellar most people have.
A cheap wine fridge set to its warmest setting, which is usually 54F to 58F. This is the only purchase in the class and it is optional.
A cardboard box with the flaps closed, sitting on the floor rather than a shelf. Floors are cooler than head height, and the box solves the light problem for nothing.

The three bottle rule

Buy three bottles of the same beer from the same year. Write the year on each one with a marker, because the printed date will rub off or hide under the box.

Drink the first this week. Write down three words for what you smell and three for what you taste. Three words, not a paragraph.
Drink the second in a year, next to your notes. Better still, buy a fresh bottle of that year's release and drink them side by side.
Drink the third at three years, the same way.

That is the whole method. It costs about the price of one round and it answers the question for your palate rather than somebody else's.

Worked example: What a year did to one bottle

Two bottles of the same imperial stout. One bought last week, one kept upright in a dark cupboard at about 55F for a year. Poured side by side into two glasses.

Look. Almost identical. Ageing does very little to the colour of a beer this dark, and the head on the older one is slightly smaller.
Smell the fresh one. Coffee, dark chocolate, a little burnt sugar, and a warm alcohol note at the top.
Smell the aged one. The coffee has stepped back. Raisin, fig and a faint sherry note have stepped forward, and the alcohol is no longer the first thing you meet.
Taste both. The aged bottle is rounder and a shade drier, and the roast bitterness is softer at the end.
Ask the only question that matters: which one do you want the rest of the glass of.

Nothing was added and nothing spoiled. The beer moved along a line from roast towards dried fruit, and where you want to sit on that line is a preference. That is what a year does to a beer that can take it.

How to tell it has gone too far

Wet cardboard is winning. A little papery note in a ten year old bottle is normal. When it is the first thing you smell, the beer has passed.
The carbonation has gone. A flat, still, syrupy mouthful means the seal or the yeast gave up.
The sherry has taken over everything. Sherry is pleasant at a whisper and tiring at a shout.
It tastes thin. Ageing dries a beer out. Past a point there is not enough left to hold it together.

Keep a note, not a spreadsheet

A photo of the bottle with three words typed underneath is enough, and it is the difference between an experiment and a vague memory. People who keep beer and take no notes end up with opinions they cannot check, which is how most bad advice about cellaring gets made.

Covered in Module P2, Faults

Why light is the fastest way to ruin a bottle. Light through clear or green glass makes the skunk smell, and heat makes cardboard. They are two different problems with two different causes. Taught once, in Module P2.

Sources: Brewers Association, Draught Beer Quality Manual, fourth edition 2019, on storage temperature and light · CraftBeer.com, Craft Beer Retailer Temperature Cheat Sheet, published by the Brewers Association

Check yourself

Before you read on. What temperature should a beer you are keeping for a year sit at, in Fahrenheit?
Answer: 53F. Think about a stone cellar under an old house. Colder than a room, warmer than a fridge.
About 50F to 55F, which is 10C to 13C, and 53F sits in the middle. Most people guess fridge cold, which is safe but slower than intended, or room temperature, which is genuinely too warm. Steadiness matters as much as the number: a cupboard that swings twenty degrees is worse than one that sits a little warm.
Sort these places by whether they are fit to keep beer in.
Answer: A cupboard against an interior wall goes in Good enough · A basement goes in Good enough · A closed cardboard box on the floor goes in Good enough · A garage goes in Bad idea · A shelf above the fridge goes in Bad idea · A windowsill goes in Bad idea
Cool, dark and steady in the first bucket. The garage swings with the weather and the shelf above a fridge sits in the warm air the fridge throws out. A windowsill adds the one thing that damages beer in hours rather than months. Nothing in the good bucket costs anything.
Bottles you are keeping should be laid on their side, as wine is.
Answer: False
False. Beer goes upright, including bottles with corks in them. Standing up keeps the sediment in a compact layer at the bottom so you can pour a clear glass, and keeps the beer off the cap. The wine habit exists to keep a cork wet, and beer bottles are sealed differently.
Put the three bottle experiment in order.
Answer: 1. Buy three bottles of the same beer from the same year and write the year on each one 2. Drink the first this week and write down three words for the smell and three for the taste 3. Drink the second a year later, next to a fresh bottle of the new release 4. Drink the third at three years and compare all your notes
Buy together, taste now, taste in a year, taste in three. The step that carries the value is the writing, because a year is far longer than anybody's memory for a smell. Buying all three at once matters too, since three bottles from three different years would be three different beers.
You open a five year old barleywine and the first thing you smell is wet cardboard. What does that tell you?
Answer: This bottle has gone past its best, whatever the style is supposed to do
It has gone past. A faint papery note in an old bottle is normal and even expected, and cardboard as the leading smell means oxidation has won. More time makes that worse rather than better. It might be the brewery, or heat somewhere on the way, and either way the bottle in front of you is done.
Which of these are signs that a kept beer has gone too far?
Answer: Cardboard is the first thing you smell · The beer is flat and syrupy · It tastes thin, with not much left holding it together
Cardboard, flatness and thinness are the three real signals, and they mean oxidation, a failed seal, and a beer that has dried past its own structure. Colour is the tempting fourth. Beer does darken very slowly with age, and in a beer that was already dark you would never notice, so it tells you nothing useful.
Your only cool dark space is a fridge at 38F. What happens to a barleywine kept there for two years?
Answer: It ages more slowly than it would in a cellar, and comes to no harm
Slower, and fine. Cold slows every reaction in the bottle rather than stopping any of them, so two fridge years are worth less than two cellar years. Nothing about the cold hurts beer, which is why the warm cupboard is always the worse option even though it feels more like a cellar.
How many bottles of the same year should you buy when you want to find out what ageing does?
Answer: 3
Three. One for now, one for a year, one for three years. Two is the tempting answer and it leaves you with no third data point and no way to see whether the trend continued. Three bottles of a national release cost about the same as one round in a bar.
Pair each condition with how much it actually matters.
Answer: A steady temperature near 55F with A great deal · Keeping the bottles in the dark with A great deal · Standing the bottles upright with Some, mostly for the sediment · Humidity and vibration with Very little for a capped bottle
Temperature and light do nearly all the damage, and both are free to fix. Humidity and vibration get talked about because the language of wine cellars was borrowed wholesale, and neither does much to a beer bottle with a crown cap on it.
A cupboard that stays at a steady 65F is a better place to keep beer than one that swings between 55F and 80F.
Answer: True
True, and it is the part people get wrong when they go looking for the perfect spot. Steadiness beats the ideal number, because every warm stretch does damage that the cool stretches do not undo. A steady 65F is warmer than you would choose and still the better of these two.

Class P3.2 done

You can name the beers worth keeping, spot the features that rule one out, set up a place for them tonight, and run an experiment that answers the question for your own palate.

The three lines worth keeping

Strong, dark, and not built on hops. All three, not one of them.
Cool, dark and upright. Steady beats perfect.
Buy three of the same year, and write three words down each time.

Class P3.3

Temperature, pouring and cask

How cold each family should actually be, how to pour a beer with a head on it, and why that head is not lost beer. Then cask, the hand pull, and what nitrogen changes.

By the end of this class you will be able to

Serve every family at a temperature that lets you taste it
Pour a beer with a proper head from a can, a bottle or a tap
Say what cask beer is, what a hand pull does, and how nitrogen differs from ordinary gas

P3.3.1 Temperature, and how to pour

Numbers by family, then the four steps, then the argument about foam.

A domestic fridge runs at about 37F to 40F, which is 3C to 4C, because that is the right temperature for milk and raw chicken. It is the wrong temperature for most beer, and it is where nearly every beer in America is stored.

Cold suppresses aroma and dulls your own sensitivity. A beer served near freezing gives your nose almost nothing to work with, which is convenient if the beer has little to say and a waste if it has.

What each family wants

One practical rule covers the whole table: everything except the first row wants ten to twenty minutes out of the fridge first.
Family	Serve at	In Celsius	Why
Mass market light lager, and anything you want mainly for refreshment	38F to 40F	3C to 4C	Cold is the point. There is little aroma to lose
Pale lager, Pilsner, Kolsch, wheat beer, non-alcoholic beer	40F to 45F	4C to 7C	Cold enough to stay crisp, warm enough for the malt and hop to show
Pale ale, IPA, amber, brown, porter, dry stout	45F to 50F	7C to 10C	This is where hop aroma actually leaves the glass
Cask ale, mild, Belgian ales, sour beers	50F to 55F	10C to 13C	Cool rather than cold, as these were designed to be drunk. Cask sits at the top of the band, at 52F to 55F
Imperial stout, barleywine, strong dark beer	50F to 55F	10C to 13C	Warm enough to open up. Very cold, these taste of almost nothing

The Brewers Association tells bars to store beer between 34F and 38F and to serve most of it between 38F and 44F. Those are draught numbers, set partly by what a cold room can do. At home you have more control, so use the table above.

It warms in your hand anyway

A pint left on a table climbs two or three degrees while you drink it, and your hand around the bowl of a glass speeds that up. This is why a beer poured slightly too cold sorts itself out, and why one poured too warm never does. If you have to miss, miss cold.

The frozen glass

A frosted glass out of a freezer is a bad idea, and the Brewers Association says so plainly. Ice on the inside makes the beer foam badly as it goes in, and the extreme cold numbs your tongue. Freezer frost also picks up the smell of whatever else is in there.

A room temperature glass is the right default for anything you want to taste. A dry, chilled glass at 36F to 40F is fine for a light lager, and the word doing the work in that sentence is dry.

The pour, in four steps

Hold the glass at about 45 degrees and start pouring against the side, not the bottom.
Once the glass is about half full, tilt it upright.
Pour straight down the middle from there. That is what builds the head.
Stop when you have about an inch of foam on top.

That is the same sequence from a tap, a can or a bottle. The first tilt stops the beer foaming out of control, and the straightening is what puts a head on it. Pouring the whole thing down the side gives you a flat glass with no smell.

The head is not waste

People ask for a beer filled to the rim because foam looks like beer they did not get. Three things argue the other way, and one of them is measurable.

Foam is mostly beer. The Brewers Association puts a foam collar at roughly a quarter to a third liquid. An inch of head costs you a fraction of an ounce, not an inch of drink.
Foam carries the smell. A 2023 study measured the air above beer before and after foaming and found several aroma compounds released far more strongly once a head had formed. The head is not sitting on the aroma, it is delivering it.
Foam is where the beer shows its condition. A head that collapses in seconds tells you something about the beer or the glass. A flat pour tells you nothing at all.

Two special cases

Bottle conditioned beer has a layer of yeast at the bottom. Pour it in one steady movement and stop when the sediment reaches the neck, unless the style wants the yeast in the glass, which is a decision the style module makes.

Highly carbonated Belgian bottles need a bigger glass and a slower hand. Pour a third, let it settle, then carry on. Fighting one of these in a small glass is how people end up wearing it.

Covered in Module F3, How to taste

The experiment that proves the temperature point. Split one beer into a cold half and a warm half and smell both. What temperature does to your perception is taught once, in Module F3. This screen is the numbers that follow from it.

Covered in Module F4, At the bar

Pour sizes, and what a pint promises. How much beer arrives is a separate question from how it is poured. Sizes, glasses and what to ask for are taught once, in Module F4.

Sources: Brewers Association, Draught Beer Quality Manual, fourth edition 2019, chapter 6 on serving draught beer · Kaneda and others, Beer Foam is a Carrier of Aroma, Journal of the American Society of Brewing Chemists, 2023 · CraftBeer.com, Craft Beer Retailer Temperature Cheat Sheet, on frosted glassware

Check yourself

Before you read on. What temperature should an imperial stout be served at, in Fahrenheit?
Answer: 53F. Your fridge is about 38F and a warm room is about 70F. This beer wants to be nearer one of those than most people think.
About 50F to 55F, which is 10C to 13C, so 53F is the middle of it. Most people guess fridge cold, because strong dark beer looks like it should be cold and heavy. At 38F an imperial stout tastes of very little, and everything you paid for arrives in the last third of the glass as it warms up.
Sort each beer into the temperature band it should be served at.
Answer: Mass market light lager goes in 38F to 42F, fridge cold · German Pils goes in 38F to 42F, fridge cold · American IPA goes in 45F to 50F, cool · Dry stout goes in 45F to 50F, cool · Barleywine goes in 50F to 55F, cellar cool · Cask bitter goes in 50F to 55F, cellar cool
The rule behind the buckets is how much aroma the beer has to give up. Pale lagers are built to be crisp and cold, hoppy and roasted beers need a few degrees to release their smell, and the strongest beers need most of all. Cask sits in the last bucket for a different reason: it was designed at that temperature rather than chilled down to it.
Why does a beer straight from the fridge smell of so little?
Answer: Cold keeps aroma compounds in the liquid and dulls your own sensitivity at the same time
Two effects pointing the same way, and both reverse as the beer warms. Nothing is destroyed, which is why the same glass smells of more ten minutes later. Cold beer does hold on to more of its gas, but that is a texture effect rather than the reason it smells muted.
Put the four steps of a proper pour in order.
Answer: 1. Hold the glass at about 45 degrees and pour against the side 2. Straighten the glass once it is about half full 3. Pour straight down the middle to build the head 4. Stop at about an inch of foam
Tilt, straighten, pour down the middle, stop at an inch. The step people skip is the second one, and skipping it is what produces a flat glass. Pouring the whole thing gently down the side keeps the gas in the liquid, which means no head, no aroma, and a beer that feels heavier than it should.
Click the part of the glass that is doing the most to get the smell of the beer to your nose.
Answer: The foam collar on top
The head. Foam forms from bubbles rising out of the beer and bursting at the surface, and each one throws aroma into the air above the glass. A 2023 study measured this directly and found several compounds released far more strongly after foaming. A flat beer smells of less because nothing is carrying the smell upwards.
A frosted glass from the freezer is a good way to keep beer cold.
Answer: False
False, on three counts. The ice inside makes the beer foam uncontrollably as it goes in. The extreme cold numbs your tongue for the first several mouthfuls. Freezer frost carries the smell of everything else in the freezer. A dry chilled glass is fine for a light lager, and a room temperature glass is right for everything you want to taste.
Which of these are genuine reasons to want an inch of foam on your beer?
Answer: Foam is roughly a quarter to a third beer, so it costs you very little liquid · Bursting bubbles carry aroma up to your nose · How the head behaves tells you about the beer and the glass
Volume, aroma and diagnosis are all real. Insulation is the tempting fourth and it does almost nothing, since a centimetre of foam is not what stands between your beer and a warm room. The strongest of the three is the aroma one, because it is the reason a flat pour tastes duller as well as looking worse.
You take an IPA out of the fridge. What should you do before pouring it?
Answer: Leave it on the counter for ten to fifteen minutes
Ten to fifteen minutes takes a beer from about 38F to around 45F, which is where its hop aroma starts arriving. Pouring immediately gives you the beer at its most muted. Hands warm the outside of a can unevenly and slowly, and you would need to hold it far longer than you think.
How much head does a properly poured draught beer carry, in inches?
Answer: 1
About one inch, which is the figure the Brewers Association gives bars. It is enough to carry the aroma and to show you how the beer behaves, and small enough that nobody is losing a meaningful amount of liquid. Filled to the rim is an overpour rather than a favour, and it costs you the smell.
Pouring a beer gently down the side of the glass the whole way is the careful, correct way to do it.
Answer: False
False. It is the way to avoid foam, which is not the same thing as the right way. Keeping the gas in the liquid gives you a flat glass with no head, a duller smell and a heavier feel in the mouth. Start against the side, then straighten and pour down the middle so the beer can release what it needs to.

P3.3.2 Cask beer and the hand pull

What cask actually is, why it is cooler and softer, and how nitrogen differs from ordinary gas.

Cask beer finishes fermenting in the container it is served from, and it is pulled by hand rather than pushed by gas. That one sentence explains the rest. It is softer, cooler and less fizzy than the same beer from a keg.

A keg arrives at the bar finished and sealed, and carbon dioxide pushes it up to the tap. A cask arrives with live yeast still working in it, and the pub finishes the job. The carbonation comes from that last quiet fermentation rather than from a gas cylinder, which is why there is so much less of it.

The fizz row is the one to remember. Cask beer has roughly half the gas of a keg beer, and that is most of the difference you taste.
	Cask	Keg
Fizz, measured in volumes of gas	0.9 to 1.2	2.5 to 2.7
Served at	52F to 55F, which is 11C to 13C	38F to 45F, which is 3C to 7C
How it reaches the glass	Pulled by a hand pump, or poured straight from the barrel by gravity	Pushed by carbon dioxide, or a blend of gas
How long once it is open	About three days	Weeks, if the bar sells it
What it feels like	Soft, round, gentle, with the flavours in front	Crisper and sharper, with the gas in front

The hand pull

The tall handle on a British bar is a beer engine, and it is a pump. Pulling it draws beer up from the cellar with no gas involved. One full pull is about half a pint, so a bartender pulling two or three times for one glass is normal rather than a sign of trouble.

Some engines have a sparkler on the spout, which is a small perforated disc. Forcing the beer through it knocks gas out and builds a thick creamy head. Northern English bars tend to use one and southern bars tend not to, and drinkers argue about it in the way people argue about ice in whisky. Neither is a fault.

Three days, and why that matters to you

Once a cask is opened, air gets in as the beer comes out, so it has about three days before it turns. A nine gallon cask holds about seventy two pints, so a pub needs to sell around twenty four pints a day of that beer to stay inside the window.

That arithmetic gives you a useful warning sign. A quiet pub with eight hand pulls is not being generous, it is being optimistic. A busy pub with two is usually the better bet.

What a good one is like, and what a tired one is like

Good. Cool but not cold, gently fizzy, clear, with a head that lasts. The malt and hop flavours arrive without the sharp bite of gas, and the beer tastes of more than its strength suggests.
Tired. A sour or vinegary edge, a flat and lifeless texture, or a cloudy glass from a cask that was moved too soon. The vinegar note is the reliable one, and it means the cask has been open too long.

Warm is not a fault. A cask ale at 55F is doing what it was designed to do, and the same beer at 38F would taste of nothing. Faulty is a different word and it has a different smell.

Nitrogen, and what it changes

Nitro beer is the other soft pour you will meet, and it gets to the same place by the opposite route. Nitrogen barely dissolves in beer, so bars use a blend of roughly one quarter carbon dioxide to three quarters nitrogen. The nitrogen pushes the beer without adding fizz to it.

The result is a beer with very little gas bite, a dense creamy head, and a soft texture. That is not a different recipe. It is a different tap, and almost any beer can be put through it.

	Cask	Nitro
Where the softness comes from	Very little gas in the beer at all	Most of the gas is nitrogen, which does not turn sharp
How it gets to the glass	Pulled by hand	Pushed by a gas blend through a restrictor plate
Temperature	52F to 55F	40F to 45F
How long it keeps once open	About three days	As long as any keg

Warm, flat English beer

The phrase gets used as an insult and it is a description of two deliberate decisions. Cool rather than cold, so the flavours are available. Gently carbonated rather than sharp, because the gas came from the beer itself.

The second half of the myth is worth correcting too. Cask beer is not stronger, older or heavier than keg beer. Most British cask ale sits between 3.5% and 4.5%, which is weaker than the average American craft beer.

Where you will actually meet these

Cask, in Britain and Ireland. Ordinary. Look for the tall handles on the bar and ask what is on today.
Cask, in the United States. Uncommon, and worth seeking out. British style pubs, a few brewery taprooms, and beer festivals. A hand pull on the bar is the sign, and it is fair to ask whether it is a real cask.
Nitro, everywhere. Guinness Draught is the beer most people meet it through, and the cans contain a small plastic widget that releases nitrogen when you open them. Left Hand Milk Stout Nitro is the widely stocked American version, sold in bottles and cans.
Nitro on tap. A separate faucet with a restrictor in it, usually with a badge saying nitro. The pour is slow, the beer looks cloudy for a moment, and then it clears from the bottom up.

Covered in Module 6, Porter and stout

Why the bubbles appear to fall in a nitro stout. Tiny nitrogen bubbles plus a glass whose wall slopes. The physics of the cascade is taught once, with Irish Stout, in Module 6.

Covered in Module F2, How beer is made

Cask, keg, can, bottle and nitro as packages. What each container does to the beer inside it is taught once, in Module F2. This screen is what happens at the bar.

Sources: Brewers Association, Draught Beer Quality Manual, fourth edition 2019, appendix D on serving cask ale and chapter 4 on nitrogenated beer · Cask Marque, on what an assessor checks, including the 11C to 13C temperature specification and the three day window

Check yourself

What makes a beer cask beer?
Answer: It finishes fermenting in the container it is served from, and is pulled rather than pushed
It is a way of packaging and serving beer, not a recipe or a temperature. The live yeast finishing its work in the cask makes the carbonation, and the hand pump moves the beer without gas. Warm and unfiltered are consequences rather than the definition, and any beer at all can be put into a cask.
Before you read on. A keg beer carries about 2.6 volumes of carbon dioxide. How many does a cask beer carry?
Answer: 1volumes. Think about how a cask pint feels against a lager: gentle rather than prickly, but not still like water.
About 0.9 to 1.2 volumes, so roughly half to a third of a keg beer. Most people guess higher, because a cask pint still has a head on it and still feels alive. That head is built by the pump and the sparkler rather than by dissolved gas, which is why it can look lively and feel soft at the same time.
Cask ale is stronger than most keg beer.
Answer: False
False, and usually the reverse. Most British cask ale sits between 3.5% and 4.5%, which is weaker than the average American craft beer. It tastes of more than that suggests because the low carbonation leaves the flavours uncovered, and because it is served warm enough to smell.
Pair each feature with cask or nitro.
Answer: Pulled up from the cellar by a hand pump with Cask · Pushed by a blend of about three quarters nitrogen with Nitro · About three days once it is opened with Cask · A dense creamy head from a restrictor plate with Nitro
Both give you a soft, low fizz pint and they arrive there by opposite routes. Cask has almost no gas in it at all. Nitro has plenty of gas, most of which is nitrogen, and nitrogen does not turn into the mild acid that gives carbon dioxide its bite.
A quiet neighbourhood pub on a Tuesday afternoon has eight hand pulls on the bar. What does that tell you?
Answer: Some of those casks have probably been open longer than three days
Arithmetic rather than cynicism. A cask has about three days once it is open, and a nine gallon cask is about seventy two pints, so each line needs roughly twenty four pints a day. Eight lines in a quiet pub cannot all be turning over. Two well kept lines beat eight tired ones every time.
Which of these mean a cask pint has actually gone wrong, rather than simply being cask?
Answer: A sharp vinegary edge · A flat, lifeless texture with no head at all · It arrives cloudy and stays cloudy
Vinegar, lifelessness and haze are the three real problems, and the first is the most reliable: it means air has been getting in for too long. Being cool is the style rather than the fault. A cask ale at 55F is doing exactly what it was designed to do, and sending it back for that would be a mistake.
What is the tall handle on a British bar called, the one that pumps beer up from the cellar?
Answer: beer engine
A beer engine, also called a hand pull or hand pump. It is a piston pump, and one pull moves about half a pint, which is why a bartender may pull two or three times for a single glass. The sparkler is the small perforated disc some of them wear on the spout.
You liked a nitro stout and want the same softness in a beer you can buy in a shop. What do you look for?
Answer: A can or bottle labelled nitro, which will have a widget or pouring instructions
Look for the word nitro on the package, because the softness came from the gas rather than the recipe. The same beer in an ordinary can will taste sharper and thinner, which surprises people who assumed they liked the beer rather than the pour. Strength has nothing to do with it.
Sort each statement by whether it describes cask beer or a keg beer on ordinary gas.
Answer: About one volume of gas goes in Cask · Served at 52F to 55F goes in Cask · Still has live yeast working in it goes in Cask · About 2.6 volumes of gas goes in Keg on carbon dioxide · Served at 38F to 45F goes in Keg on carbon dioxide · Sealed and finished before it leaves the brewery goes in Keg on carbon dioxide
Three pairs, and each pair is one decision. Where the gas came from decides how much of it there is. Whether the yeast is still working decides whether the pub is finishing the beer. Both of those together decide the temperature, because a cask has to be warm enough for the yeast to have done its job.
Guinness Draught in a can gets its texture from a small plastic widget inside the can.
Answer: True
True. The widget holds nitrogen under pressure and releases it when you open the can, which is what produces the dense head and the soft feel from a package rather than a tap. It is the easiest way to meet a nitro pour without leaving the house, and Left Hand Milk Stout Nitro is the American equivalent on most shelves.

Class P3.3 done

You can put every family at the right temperature, pour a beer with a head that earns its place, and tell cask from keg from nitro by what is in the glass.

The three lines worth keeping

Everything except a light lager wants ten minutes out of the fridge.
Tilt, straighten, pour down the middle, stop at an inch.
Cask finishes fermenting in the container it is served from, and is pulled rather than pushed.

Class P3.4

Glassware, and when it matters

An honest ranking. A clean glass changes the beer more than any other decision on this screen, the temperature of the glass comes next, and the branded glass comes last.

By the end of this class you will be able to

Test any glass for cleanliness in two seconds, and say what a dirty one does to your beer
Rank what actually changes the beer against what is tradition and marketing
Name the common glasses, say what each is for, and pick two that cover everything at home

P3.4.1 The clean glass, and the honest ranking

What actually changes the beer, in order, and the two second test that catches the biggest problem.

Glassware advice usually starts with pictures of eleven different glasses. That is the wrong end. Here is the whole subject in one table, in the order that your attention is worth spending.

Read the first row twice. It is worth more than the other four together.
What you could change	How much it does	What it changes
Whether the glass is clean	A great deal	Head, lacing, aroma, and how the beer looks from the first second. This is the only item on the list you can get badly wrong
Whether the glass is dry and near room temperature	Quite a lot	A wet or frozen glass foams uncontrollably and then goes flat, and freezer frost brings its own smell
Whether you can get your nose over the beer, with room left in the glass	Some	How much aroma reaches you. A glass filled to the rim has nowhere to hold a smell
How the glass is built: curved, straight, stemmed, tall	A little, and partly expectation	Foam behaviour, how quickly you drink, and what you expect before you taste. Measurable, and smaller than the trade suggests
Whether it carries the right brewery logo	Nothing	Nothing in the beer. Sometimes the branded glass happens to be a good one, which is a coincidence rather than a mechanism

What beer clean means

A beer clean glass has no film on the inside. Fat, oil, lipstick, milk, and the residue left by ordinary washing up liquid all leave a layer you cannot see. That layer kills foam on contact and gives bubbles somewhere to stick.

You can spot a dirty glass without touching it. Bubbles clinging to the inside wall in a random scatter mean the glass, not the beer. A clean glass shows almost none. Gas comes out of the liquid at tiny rough spots and specks, and a smooth clean wall offers very few of them.

That is not a guess. Work on champagne used a high speed camera through a microscope to watch where bubbles are born. Nearly all the streams started on tiny hollow fibres about a tenth of a millimetre long, left behind by cloth or dust. Take those away and the streams largely stop.

The three tests

Sheeting. Wet the glass. On a clean one the water forms an even film. On a dirty one it breaks into separate droplets.
Salt. Sprinkle salt down the inside of a wet glass. It sticks evenly to clean areas and skips the greasy patches.
Lacing. Drink normally. A clean glass leaves rings of foam clinging in parallel bands after each mouthful. A dirty one leaves a random smear or nothing.

The first two are for a bar or a kitchen. The third is the one you will actually use, because it happens by itself while you drink.

Washing beer glasses at home

Wash them on their own, not in water that has had greasy plates in it.
Use a small amount of unscented washing up liquid, or none at all if they are only lightly used.
Rinse in hot water, thoroughly. Detergent residue is the single most common cause of a dead head at home.
Air dry upside down on a rack. Do not dry them with a towel, which leaves fibres and smells behind.
Store them somewhere that does not smell of anything, and not rim down on a cloth.

The dishwasher question

A dishwasher is fine for beer glasses, with one caution: rinse aid and heavily perfumed tablets can leave exactly the sort of film this screen is about. If your heads die fast at home and you cannot work out why, wash two glasses by hand and compare.

Bars that take this seriously use a separate machine for glassware and never put food plates through it. That is the reason, in one sentence.

Covered in Module P2, Faults

When the glass is the problem rather than the beer. Bubbles clinging to the side and a head that dies in seconds point at the glass. What to do about a bad pint is taught once, in Module P2.

Sources: Brewers Association, Draught Beer Quality Manual, fourth edition 2019, page 55, Testing for Beer-Clean Glass · Liger-Belair, Marchal and Jeandet, Close-up on Bubble Nucleation in a Glass of Champagne, American Journal of Enology and Viticulture, 2002 · Kaneda and others, Beer Foam is a Carrier of Aroma, Journal of the American Society of Brewing Chemists, 2023

Check yourself

Your beer arrives with small bubbles clinging all over the inside of the glass. What does that tell you?
Answer: The glass has a film on it and was not properly cleaned
The glass. Gas comes out of the liquid at tiny rough spots and specks, so a clean wall gives it almost nowhere to gather. Blaming the carbonation is the tempting answer, because the bubbles are made of gas from the beer, and the tell is that they are stuck rather than rising.
Click the part of the picture where clinging bubbles tell you the glass was not properly washed.
Answer: The inside wall of the glass
The inside wall. A scatter of bubbles stuck to it means there is a film there for them to hold on to, and that film is also quietly killing your head. Sediment at the bottom is a different thing entirely, and in a bottle conditioned beer it is supposed to be there.
Put the glass washing steps in the order that actually protects a head.
Answer: 1. Wash the glasses on their own, away from greasy plates 2. Use a small amount of unscented detergent 3. Rinse thoroughly in hot water 4. Air dry upside down on a rack rather than with a towel
Separate, gentle, rinsed, air dried. The rinse is the step that carries most of the value, because detergent residue is the commonest cause of a dead head at home. The towel is the step people are proudest of and it is the one actively making things worse, since it leaves fibres and smells behind.
Bubbles in a glass of beer mostly form on the smooth glass itself.
Answer: False
False. They form at tiny imperfections and specks: dust, fibres, scratches and residue. Work on champagne using a high speed camera found nearly all bubble streams starting on hollow fibres about a tenth of a millimetre long, left behind by cloth or dust. That is also why a glass dried with a towel produces so many streams.
Pair each test with what a clean glass does.
Answer: Sheeting with Water forms an even film rather than breaking into droplets · Salt with Salt sticks evenly all the way down the inside · Lacing with Foam leaves parallel rings after each mouthful · No test at all with Bubbles do not cling to the inside wall
Three deliberate tests and one you get for free. Lacing is the one worth learning, because it happens while you drink and needs nothing from you. A bar that produces beautiful lacing on every glass is telling you something about the rest of its housekeeping too.
Which of these leave a film that kills the head on a beer?
Answer: Washing up liquid that was not rinsed off · Grease from plates washed in the same water · Lipstick
Detergent, fats and cosmetics all leave a layer that collapses foam on contact. Hard water leaves marks and cloudiness rather than an oily film, so it looks bad and does very little to the beer. Detergent is the one to watch at home, because people use too much of it and rinse too little.
Which of these changes the beer in your glass most?
Answer: Whether the glass is clean
Cleanliness, by a long way, and it is also the only one you can get badly wrong. A greasy glass takes away the head, the lacing and a share of the aroma at once. How a glass is built does something smaller, and the logo does nothing at all beyond making the photograph nicer.
A glass straight out of the freezer is the best way to serve any beer.
Answer: False
False. Frost makes ice on the inside, which makes the beer foam wildly and then go flat, and it numbs your tongue for the first several mouthfuls. Freezer frost also carries the smell of everything else in the freezer. Dry and chilled is fine for a light lager, and room temperature is right for anything you want to taste.
What is the two word trade term for a glass with no invisible film on the inside?
Answer: beer clean
Beer clean. It is a specific standard rather than a compliment, and it means free of the fats, oils and detergent residue that kill foam, not simply free of visible dirt. A glass can look spotless and fail all three tests on this screen.
Your heads collapse in seconds at home, on beers that behave properly in bars. What do you check first?
Answer: Whether detergent is being left on the glasses
Detergent, because the pattern points at you rather than the beer. When the same beers behave in a bar and fail at home, the variable is your kitchen. Age would show up in the bar as well, and how a glass is built moves foam a little rather than removing it entirely.

P3.4.2 The glasses, and what the evidence says

Seven glasses and what each is for, then the honest account of how much any of it changes the beer.

Seven glasses. Two of them, the tulip and something tall, will cover every beer in this course.
Glass	What it looks like	What it is for	Beers
Stange	A narrow straight cylinder, small	Keeps a delicate beer cold and fresh by making you drink it fast, in small servings	Kolsch, Altbier
Willibecher	A tumbler with a bulge near the top	The German workhorse. The bulge holds the head and makes it easy to grip	Pils, Helles, most German lager
Weizen vase	Tall, narrow at the base, flaring at the top	Gives a very large head somewhere to go, and shows the cloudy body off	Hefeweizen, Weizenbock
Tulip	A bowl on a stem, narrowing then flaring at the rim	Traps aroma above the beer and supports a head. The most generally useful glass there is	Belgian ales, sours, strong beer, anything aromatic
Snifter	A short wide bowl, small volume	Holds a strong aroma in and keeps the pour small	Imperial stout, barleywine
Shaker pint	A straight sided cone, wide at the top	Cheap, stackable, and the other half of a cocktail shaker	Whatever the bar is pouring
Tumbler	Short, thick walled, often six sided	Thick walls and a wide mouth. Traditional rather than technical	Witbier, some Belgian beers

What the evidence actually shows

Three findings are worth having, and none of them says what the trade says.

A curved glass makes beer taste fruitier, and part of that is expectation. In a 2017 study, 53 people rated the same beer in a curved glass and a straight one. The curved glass version was rated fruitier and more intense. The authors connect that to a known habit of the mind: people match curves with fruitiness and angles with sharpness, before tasting anything.

A curved glass makes you drink faster. A 2012 experiment used 159 people. They took about 60% longer to finish a full glass of lager from a straight glass than from a curved one, and they misjudged the halfway point of the curved glass. If a glass changes anything reliably, it is your pace.

One glass effect is pure physics. The falling bubbles in a settling nitro stout need a wall that narrows towards the bottom. Simulations and experiments published in 2013 showed that a container which widens downwards produces the opposite flow and no visible cascade. That is a real, measurable, glass driven effect, and it applies to exactly one kind of beer.

Put together, the honest summary is this. How a glass is built changes how much foam you get, how much aroma is held above the beer, how fast you drink, and what you expect before the first mouthful. It does not change the liquid.

The branded glass

A brewery glass with a logo on it does nothing to the beer that the same glass without a logo would not do. The glass is a marketing object, and a good one: it is why bars have them and why you can buy them.

The honest exception is that some brands ship a genuinely well suited glass. A Belgian tulip, a weizen vase and a stange really are the right builds for those beers. You are getting the benefit of the build, not the badge.

The shaker pint

The straight sided American pint glass is the most common beer glass in the country and the least good one. It is wide at the mouth, so aroma leaves. It is thin walled, so it warms quickly. It is straight sided, so it holds neither foam nor smell, and it chips at the rim because bars stack them.

It is everywhere because it costs very little, stacks, survives a dishwasher, and doubles as half of a cocktail shaker. None of those reasons is about beer. Your pint is not ruined by one, and if a bar offers you a choice, take the other glass.

Two glasses for home

A tulip, or a large wine glass you already own. It holds a head, gathers aroma, and works for everything from a sour to an imperial stout. Filled halfway, it is the most useful beer glass in the house.
Something tall and simple, holding about a pint. A willibecher or any clean straight glass. For lagers, wheat beers and anything you want cold and refreshing.

Buy a snifter and a weizen vase later if you drink those styles often. Do not buy eleven glasses. Buy two and wash them properly, which brings you back to the first screen.

Beers where the glass is doing real work

Guinness Draught, in a tapered pint. The cascade needs that inward slope, and a straight sided tumbler largely kills it.
Weihenstephaner Hefeweissbier, in a weizen vase. The head on this beer is enormous and the glass exists to hold it.
Duvel, in a tulip. Famously vigorous carbonation and a huge head, and the glass is built around both.
Reissdorf Kolsch, in a stange. A small glass for a delicate beer, so it is drunk before it warms up.
Orval or Chimay, in a stemmed goblet. Aromatic beers where keeping your hand off the bowl genuinely helps.

Worth remembering

Clean, dry, room temperature, room to spare. Then worry about the glass.

Four conditions in the order they matter, and all four are free. Clean beats every other decision on this screen. Dry and near room temperature stops the foam going wrong. Room to spare means not filling to the rim, so there is space above the beer for a smell to sit in. Only after those four does it matter whether you are holding a tulip or a pint.

Covered in Module 4, Wheat beers

The one style where the glass is not optional. A wheat beer builds a head several inches deep, and the tall weizen vase exists to hold it. Taught with the style, in Module 4.

Sources: Mirabito, Oliphant, Van Doorn, Watson and Spence, Glass shape influences the flavour of beer, Food Quality and Preference, 2017 · Attwood, Scott-Samuel, Stothart and Munafo, Glass Shape Influences Consumption Rate for Alcoholic Beverages, PLoS ONE, 2012 · Benilov, Cummins and Lee, Why do bubbles in Guinness sink, American Journal of Physics, 2013 · Brewers Association, Draught Beer Quality Manual, fourth edition 2019, on glassware handling and storage

Check yourself

Click the glass built to hold the enormous head of a German wheat beer.
Answer: Weizen vase
The weizen vase. It is tall, narrow at the base and flared at the top, and that flare is there because a Hefeweizen builds a head several inches deep. A shaker pint works and you will lose foam over the edge, which is the difference between a glass that copes and one that was designed for the job.
What did the 2017 study of curved and straight beer glasses actually find?
Answer: The same beer was rated fruitier and more intense in the curved glass, partly because people expect curves to mean fruit
A real difference in ratings, with expectation doing part of the work. People match curved outlines with fruitiness before they taste anything, so the glass changes the judgement rather than the liquid. That is not nothing, since your experience is what you are buying, and it is a smaller claim than the trade usually makes.
Before you read on. In one experiment, people drank a full glass of lager more slowly from a straight glass than a curved one. By how much, as a percentage?
Answer: 60%. Think about how hard it is to judge how much is left in a curved glass, and what that does to pacing.
About 60% slower from the straight glass, in a study of 159 people. The same people also misjudged the halfway point of the curved glass, which is the likely reason. Most people guess something small, because the idea that a glass changes your pace by that much feels unlikely until you try to judge half of a curved one.
Pair each glass with what it is for.
Answer: Stange with A small narrow glass so a delicate beer is drunk before it warms · Weizen vase with Somewhere for a very large head to go · Snifter with Holding a strong aroma in over a small pour · Shaker pint with Being cheap and stacking well
Three of these were designed around a beer and one was designed around a bar. The shaker pint answer is the honest one: it is wide at the mouth, thin walled and straight sided, so it does nothing for aroma, temperature or foam. It is not a disaster, it is simply not trying.
You are buying one glass for strong dark beer, a Reissdorf Kolsch and a Belgian ale. Click the one that covers the most of that.
Answer: Tulip
The tulip. It holds a head, narrows to gather aroma and flares at the rim, and it works from a sour to an imperial stout. The snifter is the tempting answer and it is too small and too specialised for a Kolsch. If you own one beer glass, own this one, and a large wine glass is a fair substitute.
Which of these does the build of a glass reliably change?
Answer: How much foam the beer keeps · How much aroma is held above the beer · How quickly you drink
Foam, aroma space and pace are all real and all measured. Bitterness is in the beer and no glass moves it. This feels wrong because people genuinely report tasting a difference. The honest explanation for most of that is aroma and expectation, rather than any change in the liquid.
The brewery logo on a glass is part of what makes the beer taste right.
Answer: False
False. The badge does nothing that the same unbranded glass would not do. The honest part of the story is that a brewery which ships a glass usually ships a well suited one, so you get the benefit of how it is built. Buy a good tulip and you have all of that benefit and none of the logo.
Sort each claim by whether the evidence supports it.
Answer: A clean glass changes the head and the aroma goes in Supported · A curved glass changes how fast people drink goes in Supported · A tapered glass is needed for the cascade in a nitro stout goes in Supported · Each style needs its own dedicated glass goes in Mostly tradition or marketing · A branded glass improves the beer goes in Mostly tradition or marketing · Thick glass keeps beer cold for a long time goes in Mostly tradition or marketing
Three of these have published work behind them and three do not. The last one is the closest call. Thick walls do slow warming a little, and the effect is small next to the temperature the beer started at and how long your hand is wrapped around the glass.
Which single feature of a glass matters more than everything else about it?
Answer: clean
Clean. A film of grease or detergent kills the head, takes a share of the aroma with it and covers the glass in clinging bubbles. Everything else on this screen is a smaller effect, and this is the only one you can get badly wrong without noticing.
Why is the shaker pint the standard glass in American bars?
Answer: It is cheap, it stacks, and it is half of a cocktail shaker
Cost, storage and a second job behind the bar. None of those reasons is about the beer. It was not designed for beer at all. It does not measure anything reliably either, once you allow for the head, and pour sizes are taught in Module F4.

Class P3.4 done

You can test a glass in two seconds and say what a dirty one costs you. You can also rank the rest of the subject honestly, and pick two glasses that cover every beer in the course.

The three lines worth keeping

Clean, dry, room temperature, room to spare. Then worry about the glass.
Bubbles clinging to the side mean the glass, not the beer.
A tulip and something tall will serve every beer in this course.