Clear Beer, Part 1

Use kettle finings to pull proteins from your wort and help produce clearer beer.

Dave Carpenter May 31, 2015 - 4 min read

Clear Beer, Part 1 Primary Image

In a recent Web-exclusive article on, I addressed a few of the reasons that you might turn out a hazy brew here and there. One of the culprits I mentioned was chill haze, a mostly harmless condition in which proteins and tannins huddle together in the cold and obscure your pint. Maintaining a healthy, rolling boil, followed by rapid cooling can help reduce haze, but a complementary approach is to use a fining agent.

Finings are added to wort or beer to promote clarity in the finished product, and there are two broad classes. Kettle finings are added while wort continues to boil away in the kettle, whereas fermentor finings are added to finished beer. We’ll focus on kettle finings for now and discuss fermentor finings next week.

Kettle finings are almost always made from Chondrus crispus, more commonly called Irish moss, a red seaweed that contains a great deal of carrageenan. Carrageenan, in turn is a type of polysaccharide (carbohydrate) that is widely used in the food industry as a thickener. Many vegan products make use of the carrageenan in Irish moss as a non-animal alternative to gelatin. Even affirmatively non-vegan products such as yogurt and ice cream often include carrageenan as an inexpensive thickener.

So what does this have to do with clear beer? Well, as it happens, carrageenan carries a fairly strong negative charge and is all too eager to bond with positively charged proteins floating around in wort. When carrageenan is introduced into boiling wort, it matches up with said positive proteins and, upon cooling, forms large clumps that precipitate out of suspension and fall to the bottom of the kettle.


Brewers who rely on immersion wort chillers will recognize this phenomenon immediately as the cold break, that “miso soup” phase when cloudy clumps separate out and leave behind a crystal clear liquid. Carrageenan enhances the cold break, and many first-time homebrewers are surprised at just how much of this fluffy crud flocculates out.

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Pure Irish moss (top, right) is available from homebrew retailers everywhere and couldn’t be easier to use. Simply hydrate one teaspoon per five gallons of wort in a small amount of water for a few minutes, and then add it to the kettle within the last 10 to 15 minutes of the boil. That’s it. If you cool your wort quickly enough, the cold break will be obvious and substantial.

Whirlfloc tablets (top, left), another type of kettle fining, are made from Irish moss and bear a mild physical resemblance to chewable antacids. Many brewers prefer these tablets to the plain algae because they’re pre-measured, and no hydration is necessary. It has also been my personal (though by no means universal) experience that Whirlfloc creates a better cold break than Irish moss in its unprocessed form. It’s also more expensive, so try both and decide which you prefer.

Kettle finings do a great job of pulling proteins from wort, but what about finished beer? Next week we’ll take a look at some of the finings that brewers use to remove proteins and yeast before packaging their beer.