Filter paper

Filter paper

Filter paper is a semi-permeable paper barrier placed perpendicular to a liquid flow. It is used to separate fine solids from liquids. In laboratories, filter paper is usually used with a filter funnel, Hirsch, or Buchner funnel.


Filter paper comes in various porosities and grades. Different manufacturers have different standards, usually identified by parameters such as porosity, particle retention, and flow rate.

Choice of filter paper for a given task depends on four parameters: strength, compatibility, efficiency and capacity. A coffee filter is an adequate example to evaluate these parameters and how they affect performance and results.

If a coffee filter doesn't possess enough "strength", it will tear or rupture, and many of the coffee grains will collect in the coffee pot. "Compatibility" describes a filter medium's resistance to degradation by heat and chemical attack; a filter that is not compatible with the liquid passing through it is likely to break down, losing strength (structural failure). (Filters made of certain plastics may not be compatible with organic solvents, for instance.)

"Efficiency" is the retention of particles in a target (size) category. The efficiency required is dictated by the particles or substances trying to be removed. A large-mesh filter may be very efficient at retaining large particles (e.g., leaves), but inefficient at retaining small particles (e.g., fine crystals, blood cells).

"Capacity" is the ability to "hold" previously removed particles while allowing further flow. A very efficient filter may show poor capacity, causing increased resistance to flow or other problems as it plugging up prematurely and increasing resistance or flow problems. A balance between particle capture and flow requirements must be met while ensuring integrity.

Filter paper is also sometimes called chromatography paper. Chromatography paper is pure white, so that colored compounds can be seen more easily. There are a number of different types of filter paper for specific applications: chemical analysis filter paper, qualitative filter paper, ashless filter paper, air filter paper, engine oil filter paper, fuel filter paper, etc.

Ashless filter paper is mainly used for gravimetric methods in quantitative chemical analysis. It has a base weight of 80 g/m2Fact|date=June 2008.

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Look at other dictionaries:

  • Filter paper — Filter Fil ter, v. t. [imp. & p. p. {Filtered}; p. pr. & vb. n. {Filtering}] [Cf. F. filter. See {Filter}, n., and cf. {Filtrate}.] To purify or defecate, as water or other liquid, by causing it to pass through a filter. [1913 Webster] {Filtering …   The Collaborative International Dictionary of English

  • filter paper — pā pər n porous unsized paper used esp. for filtering * * * a porous, unsized paper used as a filter …   Medical dictionary

  • filter paper — n. porous paper for filtering liquids …   English World dictionary

  • filter paper — filtravimo popierius statusas T sritis chemija apibrėžtis Įvairaus tankio bepelenis, skysčiams laidus popierius. atitikmenys: angl. filter paper rus. фильтровальная бумага …   Chemijos terminų aiškinamasis žodynas

  • filter paper — paper used by chemists for filtering …   English contemporary dictionary

  • filter paper — UK / US noun [uncountable] science paper that is used in a filter for removing solid parts that are not wanted from a liquid or gas that passes through it …   English dictionary

  • filter paper — noun a porous unsized paper used for filtering (Freq. 1) • Hypernyms: ↑paper …   Useful english dictionary

  • filter paper — noun Date: circa 1846 porous unsized paper used especially for filtering …   New Collegiate Dictionary

  • filter paper — porous paper used in filtering. [1890 95] * * * …   Universalium

  • filter paper — noun porous paper used for filtration …   Wiktionary