Floor Malting was the traditional way of producing malt for brewing before the Industrial Revolution. It was largely a manual process, and today floor malting is considered a niche artisanal practice. A few specialty maltsters in the UK, Germany, and the Czech Republic continue to make floor malts available to brewers, who prize them for the deep, rich flavors. In floor malting, just as in modern mechanized malting, the incoming grain is first steeped in large vats, in an alternating series of “wet” and “dry” cycles. See malt. Once properly hydrated, the malt is then sent not to a germination chamber, but to a “floor,” where it is spread evenly by hand into an approximately 15 cm (6 inch) thick layer. The favored floor material for European floor maltings has always been tiles quarried only in the Bavarian village of Solnhofen. This stone is hard and thin, with excellent thermal dispersion, moisture retention, and wear resistance. British floor maltings have retained their own types of stone floors. While on the floor, the germinating grain must be turned by hand twice a day, 7 days a week, to keep it properly oxygenated, to dissipate heat, and to keep rootlets from tangling the malt into an unmanageable mat. The traditional tools for this hard labor are a wooden malt shovel and a special, iron-wrought rake that often weighs up to 70 lb (30 kg). The rake, dragged arduously through the malt, is simply called a “malt rake” or “puller” in the UK, but in Germany it is known by the very strange name of “wohlgemut,” meaning “pleasant disposition.” At the proper germination stage, when the acrospires have grown almost as long as the barley kernels, the moist, green malt is sent to a kiln, where it is spread by shovels in a one-half meter (not more than two feet) thick layer. From then on, the drying process proceeds much as it does in a modern kiln, except very slowly, for perhaps 32 to 48 hours rather than the 24 hours that are now common in industrial malting. The temperature in an old-style kiln with floor malt rarely exceeds 85°C (185°F).
Traditional floor malting, unlike modern malting, takes place without any artificial ventilation, which is why green floor malt beds tend to contain more CO2 than do beds in modern plants. The entire floor malting process, therefore, leaves the malt slightly “under-modified” by modern standards, but it gives the malt a very rich, aromatic flavor that is far more intense than is usually achieved by today’s time-efficient, industrial malting procedures. See modification. While modern malting plants with mechanized controls can operate year-round, traditional floor malting is not possible during the summer, because barley germinates unevenly once the ambient temperature rises above 14°C (57°F). Uneven germination would cause the malt to lose its pleasant flavor as well as its favorable processing qualities in the mash.