Cellulose is a polysaccharide which is obtained from the wood of fir or beech trees. The wood is shredded and then boiled, lignin and pektin are removed and it is then bleached.

Cellulose fibers have a thickness between 25 and 75 µm. Cellulose contains water in two forms - 7% as water of hydration and up to 25% held in the structure by capillary action. The filter layers can contain between 30% and 50% by weight depending on the level of clearness.