Surface filtration (hyomen roka)

Surface filtration is a method of filtering suspended matter out of a liquid using a filter medium. The layer that forms as suspended particles build up on the surface of the filter medium is called a "filter cake." This filter cake forms on the surface of the medium and grows thicker as filtration proceeds, which can eventually affect the efficiency of the filtration. In sake production, surface filtration is sometimes used to obtain a clear sake. By removing excess impurities through filtration, it can bring out the smooth, rich flavor characteristic of sake.