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Filtration
After cold conditioning the beer is passed through a keiselghur fiter which removes the haze from the beer leaving it bright and clear.
This process involves the use of special powders called Keiselghur or diatomaceous earth which are produced from layers of rock laid down millions of years ago by the deposition of microscopic plankton on ancient sea beds. This powder is very fine but under the microscope can be seen to be composed of fragments of skeletons or shells of these tiny creatures.
The beauty of this material is that when it is slurried and made to form a bed over a wire mesh it produces a very porous base filled with millions of microscopic holes created by the tiny fragments of skeletons and shells.
The filter operates by dosing the beer with a carefully measured amounts of the keiselghur then circulating it around a series of wire mesh plates on which the keiselghur gradually builds up a filter bed. The protein/ tannin haze along with any other fine particles present either get absorbed onto the keiselghur or trapped in the many fine pores. Eventually the beer circulating round the filter becomes clear and at that point it is diverted to a Bright beer tank. Beer from the cold conditioning tank is then fed into the filter along with a measured amount of keiselghur and effectively becomes self filtering passing in as cloudy beer dosed with keiselghur and passing out of the filter as clear, bright beer.
