Steinbier, “stone beer,” an ale brewed with the use of hot stones, originally without the use of any brewing equipment made from metal. Steinbier breweries were typical for southern Austria and for some parts of Bavaria up to the beginning of the 20th century. The brewing method was supposedly developed by farmers who did not own proper brewing vessels. Heating of the mash and boiling of the wort were induced not by heating a brew kettle but rather by dropping very hot stones into wooden vessels containing the mash or the wort. Most stones are unsuitable for that procedure because sudden temperature changes result in cracking of most types of rock. A certain variety of rock, however, seems to resist extreme temperature changes; it is called “gray wacke.” This kind of stone is very common in Carinthia, the southernmost state of Austria, and it was here that steinbier was developed.
Steinbier was produced in wooden brewing vessels. Stones heated over fire were dropped into the mash tun to heat the mash; later, after the run-off, the same or a similar vessel would be used to boil the wort. The effect of adding hot rock to the mash, and even more effectively to the wort, would result in spontaneous boiling of the liquid that came in contact with the surface of the stone. Sugars from the wort would also instantly caramelize, whereas the stone itself released some of the smokiness of the fire in which it had been heated. Not surprisingly, this procedure was highly dangerous and could easily end up with the brewer burned by wort or the brewery consumed by fire.
This rather primitive production method seems to date back millennia and was widespread throughout the world, but gray wacke is particular to this part of Europe. Superheated stones have been used in farmhouse brewing for centuries, but rarely in professional brewing in towns or villages. Professional brewers refused to accept the brewers of steinbier in their guilds because the use of metal vessels was considered crucial for the craft. When state-of-the-art brewing equipment became more widely available in the second half of the 19th century, most steinbier breweries could not survive the stiff competition. Holzleger was the last steinbier brewery in Austria (and presumably in the world); it was opened in the small village of Waidmannsdorf near Klagenfurt in 1645 and was in operation until 1917, probably because of a lack of brewing material in World War I. The production was 690 hl that year.
Long after steinbier had disappeared from the map, the production technique was rediscovered by the Sailer Bräu Franz Sailer in Marktoberdorf, Bavaria. Here gray wacke rocks were put into large metal cages, heated over beechwood, and hauled into a (conventional) brew kettle. The rocks, coated with caramelized sugars, were then later added to the fermenting beer, giving it a unique blend smoke and caramel flavors. The production was given up when Allgäuer Brauhaus (a subsidiary of Radeberger) took over the brewery in Marktoberdorf in 2003. Some other breweries have taken up the production of steinbier, including Leikeim in the Franconian town of Altenkunstadt. Their steinbier is a lager with faint hints of caramel and smoke.