S-04 Safale ale yeast, what it does and when to use it

S-04 is a dry English ale yeast in an 11.5g sachet, and the short version is that it leaves malt character in the beer and then falls out of suspension hard, so you get a fuller tasting pint that still pours clear. If you've been using a neutral American strain and wondering why your bitters and your dark ales come out tasting a bit polite, this is usually the thing to change.

What it actually does differently

Every ale yeast eats the same sugars, but they don't all eat the same amount of them and they don't all leave the same things behind. S-04 finishes a touch earlier than a highly attenuative yeast does, which means a bit more residual sweetness and a bit more body in the glass, and that reads as maltiness even though the malt bill hasn't changed at all.

The other half of it is flocculation, which is the word for how readily the yeast clumps together and sinks once it's finished. S-04 flocculates strongly, so it drops into a firm layer on the bottom of the fermenter rather than hanging about in the beer. That's why it has a reputation for clearing quickly without you having to do anything about it.

Where I'd use it

• English bitters and English style ales, which is what it was bred for.
• Stouts and dark ales, where the extra body is doing you a favour.
• Anything that came out thin last time and you couldn't work out why.

Where I'd reach for something else is a crisp pale ale or an IPA, because there you usually want the hops out in front and the yeast out of the way, and a cleaner strain like US-05 does that better. Neither one is the good yeast. They're aimed at different beers.

The catch worth knowing about

The thing that makes S-04 good is also the thing that catches people out. Because it drops so hard, there can be very little yeast left in suspension by the time you come to bottle, and bottle conditioning needs live yeast to carbonate the beer. So give the fermenter a gentle stir before you bottle, or just be patient, because a batch that seems flat after a week will often come good with another week or two somewhere warm.

Temperature

I'm not going to print a range here. Fermentis print the working range on the back of the sachet, the sachet is in your hand and this page isn't, and copying a number off a blog is how people end up fermenting at somebody else's temperature. Read the packet. What I will say is that holding a steady temperature matters more than which exact number you land on, because a fermenter that swings from cold nights to warm afternoons will throw flavours you didn't ask for regardless of the yeast in it.

There's more than one way to run a fermentation and I'm always interested in how other people do theirs, so if you've got a method that works, tell us in the shop, because I want to know whether mine is the slow one.

Shop related products

• S-04 Safale Ale Yeast 11.5g. The English one, malty and quick to clear.
• US-05 Safale Ale Yeast 11.5g. The neutral one, for when the hops should lead.
• S23 Saflager Lager Yeast 11.5g. For a lager, which is a different job again.
• Coopers English Bitter 1.7kg. The obvious kit to put S-04 to work in.

Did you know we also keep cider and wine yeasts on the shelf in the shop, along with a mead yeast. None of those made it onto the website, so give us a ring on (08) 8536 4333 to check what's there.

More on brewing

• US-05 Safale ale yeast, what it does in your beer
• S23 Saflager lager yeast, when to use it
• What fermentation actually does, and how to keep yeast happy

If you'd rather talk it through than read about it, Brewhilder is our homebrew adviser, and the rest of the range sits in the homebrew collection.

Still the one I forget to take out of the fridge until the wort's already cooled.

Cheers,
Candeece