Why your homebrew has no head and goes flat fast

September 10, 2025

Why your homebrew has no head and goes flat fast

You pour it and get about a centimetre of foam, and by the time you've sat down it's gone and you're looking at a flat brown drink. The taste might be alright. It just doesn't look like beer.

The annoying thing is that this one is almost never the recipe, and people chase it by changing their hops or buying a different kit, which does nothing. It's nearly always one of four things, and they're worth checking in this order because that's roughly how common they are.

1. Something in the glass or the bottle

Start here, because it's the most common by a mile and it costs nothing to rule out. Foam is held up by proteins. Both fat and detergent residue destroy those on contact. A film of dishwashing liquid left in a glass that wasn't rinsed properly will kill a head in seconds. Rinse aid out of a dishwasher does the same thing, and so does a greasy thumb on the inside of the rim.

Test it in about a minute. Pour the same beer into a glass you've rinsed with hot water and nothing else, then pour it into a glass straight out of the dishwasher and stand the two side by side. If one holds its head and the other doesn't then you've found your problem, and there's nothing wrong with the beer at all.

Same goes for the bottles. Anything you've washed with detergent needs rinsing until it squeaks, and a bottle brush plus a no rinse sanitiser is an easier habit than trying to rinse detergent out properly every time.

2. Not enough sugar at bottling, or not enough time

The bubbles in a bottled beer come from a second small ferment in the bottle, so if you've under primed you simply haven't made enough gas. Carbonation drops take the guesswork out of that, and they're worth it for the first few batches just to eliminate the variable.

And it needs warmth and time to happen. Bottles that go straight into a cold shed in winter can sit there for weeks doing very little, so leave them somewhere that stays reasonably warm for at least two weeks before you start judging, then move them somewhere cool.

3. Not enough of the right sort of malt

Now we get to the recipe, and this is where the gap between a kit made with plain sugar and a kit made with malt shows up.

Sugar ferments out almost completely and leaves nothing behind. Malt extract doesn't, and the bits it leaves behind are proteins and dextrins, which is exactly the material foam is built out of. So a kit brewed with a kilo of plain white sugar will usually be thinner in the body and poorer in the head than the same kit brewed with malt, and you'll taste the difference as well as see it.

Swapping the sugar for a malt extract is the single biggest lever you've got here. A dark malt extract does that job and brings roast and colour with it, which is what a stout or a dark ale wants anyway. A light or amber extract does the same job for the head without pushing the colour around, so use that one when you don't want the beer to change character.

Wheat is the other classic answer here. Wheat is higher in the proteins that hold foam up, and even a small proportion of wheat malt in a batch lifts the head noticeably.

4. It's leaking

Worth a mention because it's easy to miss. A crown seal that didn't crimp properly, or a cap re-used once too often, will let gas out slowly over a fortnight and you'll open a bottle that's barely got a hiss in it. If one bottle in a batch is flat and the rest are fine, it's the cap. If they're all flat, it's one of the first three.

What to change next time

Change one thing, not four, because if you change everything at once and the next batch is better you still won't know why. Wash a glass properly and pour again first, since that's free. If it's still flat, prime with drops so you know the sugar is right. If it's still flat after that, put malt where the sugar was and you'll have both a better head and a better beer.

What you'd want for this

Coopers Dark Malt Extract 1.5kg. Lifts body and head retention. Brings roast and colour with it.
Coopers Light Malt Extract 1.5kg. Same job on body without changing the colour.
Coopers Brew Enhancer 2 1kg. Part malt, part dextrose, an easy step up from plain sugar.
Coopers Light Dry Malt 500g. A smaller amount if you just want to nudge it.

Did you know we also keep Coopers wheat malt, carbonation drops, crown seals, bottle brushes and no rinse sanitiser in the shop. They aren't all on the website, so give us a ring on (08) 8536 4333 to check what's on the shelf.

The rest of it is in our beer supplies and the wider homebrew range, and Brewhilder, our homebrew helper, will talk you through what suits your setup.