Kappa number

The Kappa number is an indication of the residual lignin content or bleachability of wood pulp by a standardised analysis method.

Measuring method

The Kappa number is determined by ISO 302:2004.[1] ISO 302 is applicable to all kinds of chemical and semi-chemical pulps and gives a Kappa number in the range of 1-100. The Kappa number is a measurement of standard potassium permanganate solution that the pulp will consume. The measurement is inflated by the presence of hexenuronic acids in the pulp. These compounds are formed during the chemical pulping process, from the hemicelluloses.

The Kappa number can be monitored by online Kappa analysers in a pulp mill, but these have to be calibrated with the ISO 302:2004 method.


The Kappa number estimates the amount of chemicals required during bleaching of wood pulp to obtain a pulp with a given degree of whiteness. Since the amount of bleach needed is related to the lignin content of the pulp, the Kappa number can be used to monitor the effectiveness of the lignin-extraction phase of the pulping process. It is approximately proportional to the residual lignin content of the pulp.

K ≈ c*l

K: Kappa number; c: constant ≈ 6,57 (dependent on process and wood); l: lignin content in percent

The Kappa number for bleachable pulps are in the range of 25-30, sack paper pulps in the range 45-55 and pulps for corrugated fiberboard are in the range 60-90.


  1. ^ "ISO 302:2004 Pulps — Determination of Kappa number". International Organization for Standardization.

External links


Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic organic compound with formula C14H8O2. Several isomers are possible, each of which can be viewed as a quinone derivative. The term anthraquinone, however, almost invariably refers to one specific isomer, 9,10-anthraquinone (IUPAC: 9,10-dioxoanthracene) wherein the keto groups are located on the central ring. It is a building block of many dyes and is used in bleaching pulp for papermaking. It is a yellow highly crystalline solid, poorly soluble in water but soluble in hot organic solvents. For instance, it is almost completely insoluble in ethanol near room temperature but 2.25 g will dissolve in 100 g of boiling ethanol.

Greek letters used in mathematics, science, and engineering

Greek letters are used in mathematics, science, engineering, and other areas where mathematical notation is used as symbols for constants, special functions, and also conventionally for variables representing certain quantities. In these contexts, the capital letters and the small letters represent distinct and unrelated entities. Those Greek letters which have the same form as Latin letters are rarely used: capital A, B, E, Z, H, I, K, M, N, O, P, T, Y, X. Small ι, ο and υ are also rarely used, since they closely resemble the Latin letters i, o and u. Sometimes font variants of Greek letters are used as distinct symbols in mathematics, in particular for ε/ϵ and π/ϖ. The archaic letter digamma (Ϝ/ϝ/ϛ) is sometimes used.

The Bayer designation naming scheme for stars typically uses the first Greek letter, α, for the brightest star in each constellation, and runs through the alphabet before switching to Latin letters.

In mathematical finance, the Greeks are the variables denoted by Greek letters used to describe the risk of certain investments.


Kappa (uppercase Κ, lowercase κ or cursive ϰ; Greek: κάππα, káppa) is the 10th letter of the Greek alphabet, used to represent the [k] sound in Ancient and Modern Greek. In the system of Greek numerals, Kʹ has a value of 20. It was derived from the Phoenician letter kaph . Letters that arose from kappa include the Roman K and Cyrillic К.

Greek proper names and placenames containing kappa are often written in English with "c" due to the Romans' transliterations into the Latin alphabet: Constantinople, Corinth, Crete. All formal modern romanizations of Greek now use the letter "k", however: Thessaloniki, Kalamata, Nikaia.

The cursive form ϰ is generally a simple font variant of lower-case kappa, but it is encoded separately in Unicode for occasions where it is used as a separate symbol in math and science. In mathematics, the kappa curve is named after this letter; the tangents of this curve were first calculated by Isaac Barrow in the 17th century.

Kraft process

The kraft process (also known as kraft pulping or sulfate process) is a process for conversion of wood into wood pulp, which consists of almost pure cellulose fibers, the main component of paper. The kraft process entails treatment of wood chips with a hot mixture of water, sodium hydroxide (NaOH), and sodium sulfide (Na2S), known as white liquor, that breaks the bonds that link lignin, hemicellulose, and cellulose. The technology entails several steps, both mechanical and chemical. It is the dominant method for producing paper. In some situations, the process has been controversial because kraft plants can release odorous products and in some situations produce substantial liquid wastes.

List of International Organization for Standardization standards, 1-4999

This is a list of published International Organization for Standardization (ISO) standards and other deliverables. For a complete and up-to-date list of all the ISO standards, see the ISO catalogue.The standards are protected by copyright and most of them must be purchased. However, about 300 of the standards produced by ISO and IEC's Joint Technical Committee 1 (JTC1) have been made freely and publicly available.

List of unusual units of measurement

An unusual unit of measurement is a unit of measurement that does not form part of a coherent system of measurement; especially in that its exact quantity may not be well known or that it may be an inconvenient multiple or fraction of base units in such systems. This definition is deliberately not exact since it might seem to encompass units such as the week or the light-year which are quite "usual" in the sense they are often used; if they are used out of context, they may be "unusual", as demonstrated by the Furlong/Firkin/Fortnight (FFF) system of units. Many of the unusual units of measurements listed here are colloquial measurements, units devised to compare a measurement to common and familiar objects.

Potassium permanganate

Potassium permanganate is an inorganic chemical compound and medication. As a medication it is used for cleaning wounds and dermatitis.It has the chemical formula KMnO4 and is a salt consisting of K+ and MnO−4 ions. It is a strong oxidizing agent. It dissolves in water to give intensely pink or purple solutions, the evaporation of which leaves prismatic purplish-black glistening crystals. In 2000, worldwide production was estimated at 30,000 tonnes. In this compound, manganese is in the +7 oxidation state.

The wholesale cost in the developing world is about US$0.01 per gram of powder. In the United Kingdom a 400 milligram tablet costs the NHS roughly £0.51.

and process

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