Perhaps the best-known kettle fining is Irish moss, a standard ingredient listed in nearly every homebrew recipe. Irish moss is a type of seaweed that was originally gathered along seashores of the North Atlantic, including Ireland — hence its common name. It’s also called carrageenan, which is the name of its active ingredient. As a kettle fining, Irish moss is added to the brew kettle, usually during the last few minutes of the boil. It helps to settle out proteins in the wort that could contribute to haze later on. Learn how to best keep your beer clear using Irish moss with Ashton Lewis, BYO’s Technical Editor.