Mashing
At the brewery the malt is milled and ground down into grist, ready for mixing with water, which is known throughout the brewing process as liquor. Hot liquor and grist mix either in the mash tun - a large, cylindrical vessel - or in a mashing machine (masher) which opens out into the tun. The thick, sludgy mix is then allowed to stand for two or three hours at a controlled temperature.
Boiling the wort
The sweet liquid mix (wort) is run off through the slotted floor of the tun, which collects the spent grains; these grains are then sprayed (sparged) with hot liquor from a revolving device within the tun, in order to flush out any remaining wort. The wort is then boiled with hops - more often now hop pellets or extract - for an hour or two in a large metal vessel known as a copper. Coppers, as the name suggests, used to be made of copper (now stainless steel), are now normally closed, and may be flat-topped or domed. A variety of heating methods have been used to boil the wort, from external direct firing with wood or coal, through steam coils to external gas firing. After boiling, the hopped wort is sent through a metal vessel with a perforated base, the hop back, which sieves out the spent hops.
Fermentation
The hot wort is then cooled before fermentation. Originally large, open shallow tanks (coolships) were used for this purpose, sited near the top of the brewery tower where good ventilation was available. Many improved forms of heat exchanger were later devised, particularly towards the end of the 19th century. After cooling, the wort is run into fermenting vessels, which used to be open wooden rounds, copper, stone or slate squares, or wooden casks. Now, closed conical fermenters are the norm. Yeast is added (pitched), and within 24 hours the surface is covered with a thick yeasty foam, which is later skimmed off. Some is reused, while the excess is compressed in a yeast press and sold to food processors. Fermentation time is typically 3 days.
Racking
The beer can then be run from the fermenting vessels directly into casks, but is usually sent to conditioning tanks, where the remaining yeast is cleared from the beer using finings. Finally, the beer is either bottled, transferred to wooden or metal casks (racked), or packaged into metal kegs or even road tankers.