The type of filter paper

Air filter paper in an auto engineMain article: Air filter

The main application for air filters are combustion air to engines. The filter papers are transformed into filter cartridges, which then is fitted to a holder. The construction of the cartridges mostly requires that the paper is stiff enough to be self-supporting. A paper for air filters needs to be very porous and have a weight of 100 - 200 g/m2. Normally particularly long fibrous pulp that is mercerised is used to get these properties. The paper is normally impregnated to improve the resistance to moisture.[1] Some heavy duty qualities are made to be rinsed and thereby extend the life of the filter.

Coffee filter[edit]Main article: Coffee filter

Coffee filters of paper are made from about 100 g/m2 crêped paper. The crêping allows the coffee to flow freely between the filter and the filtration funnel. The raw materials (pulp) for the filter paper are coarse long fiber, often from fast growing trees. Bothbleached and unbleached qualities are made. Coffee filters are made in different shapes and sizes to fit into different holders. Important parameters are strength, compatibility, efficiency and capacity.

Fuel filters Main article: Fuel filter

The paper used for fuel filters is a crêped paper with controlled porosity, which is pleated and wound to cartridges. The raw material for filter paper used in fuel filters are made of a mixture of hardwood and softwood fibres. The basis weight of the paper is 50 - 80 g/m2.