Stone beer is not only the oldest style of beer, but today is one of the newest, as the arduous process of this brew method has been painstakingly resurrected. Centuries ago, before metal or iron brew kettles, wort could only be boiled by heating stones and placing them in wooden kettles. So just how did this resurrection come about?
In 1982, Gerd Borges, a brewery executive from Northern Germany found a 1906 article about the stone brewing method, which really peaked his curiosity. Not only did he need more information about the actual method, but most importantly he needed the grau-wacke stones, a type of sandstone from Kutschachtal. These unusual stones could stand being heated to 2200 degrees F. and then cooled to 212 degrees F. without exploding, and without leaving any trace of their characteristics in the beer wort. His search led him to the son of the last brewmaster who had made a tape recording that preserved the priceless information before he passed away in 1965. Not only did the son have the wondrous tape, but he also held the deed to the sandstone quarry where the special stones were mined! Borges bought the tape and the quarry, too.
In 1982, Borges reintroduced the world to stone brewing. Using a huge open fireplace that could accommodate a steel basket that held 880 pounds of stones, he would heat the stones over a beechwood fire. (The fireplace held 212 cubic feet of wood.) The steel basket and stones were heated for 4 hours, then monorailed to another area where they were coated with caramelized sugar, cooled, and stored until the secondary fermentation.
In the brew kettle, the wort is preheated to 203 degrees F., bringing it to a full boil. The candied stones are added to the secondary fermentation, where the sugar is sloughed off the stones, leaving a smoky, caramel-like flavor to the finished beer. It’s little wonder very few breweries pursue this difficult way to brew!