mercerisation
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Mercerisation is a
textile finishing In textile manufacturing, finishing refers to the processes that convert the woven or knitted cloth into a usable material and more specifically to any process performed after dyeing the yarn or fabric to improve the look, performance, or "ha ...
treatment for
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wa ...
fabric Textile is an umbrella term that includes various fiber-based materials, including fibers, yarns, filaments, threads, different fabric types, etc. At first, the word "textiles" only referred to woven fabrics. However, weaving is not ...
and
yarn Yarn is a long continuous length of interlocked fibres, used in sewing, crocheting, knitting, weaving, embroidery, ropemaking, and the production of textiles. Thread is a type of yarn intended for sewing by hand or machine. Modern manu ...
, mainly
cotton Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor pe ...
and
flax Flax, also known as common flax or linseed, is a flowering plant, ''Linum usitatissimum'', in the family Linaceae. It is cultivated as a food and fiber crop in regions of the world with temperate climates. Textiles made from flax are known in ...
, which improves dye uptake and
tear strength Tear resistance (or tear strength) is a measure of how well a material can withstand the effects of tearing. It is a useful engineering measurement for a wide variety of materials by many different test methods. Discussion For example, with ru ...
, reduces fabric shrinkage, and imparts a
silk Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from th ...
-like luster.


Development

The process was devised in 1844 by John Mercer, who treated cotton with solutions of20–30%
sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and al ...
followed by washing. Mercer observed that the treatment shrank the fabric and increased its tensile strength and affinity for dyes. In the original process of Mercer, no tension was applied. The product was termed ''fulled cotton'', a nod to the process of
fulling Fulling, also known as felting, tucking or walking ( Scots: ''waukin'', hence often spelled waulking in Scottish English), is a step in woollen clothmaking which involves the cleansing of woven or knitted cloth (particularly wool) to eli ...
in woven wool fabric. Mercer regarded the increased affinity for dyes as the most important technical aspect. Mercer also experimented with
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular fo ...
and
zinc chloride Zinc chloride is the name of inorganic chemical compounds with the formula ZnCl2 and its hydrates. Zinc chlorides, of which nine crystalline forms are known, are colorless or white, and are highly soluble in water. This salt is hygroscopic ...
solutions and discovered the
parchmentising Parchmentising or parchmentizing is a kind of aesthetic finish for textiles. It is a finishing treatment for cellulose fabric that stiffens the fabric and imparts a degree of translucency. Parchment Parchment was a material for writing created ...
effect of sulfuric acid. The silk-like lustre now commonly associated with mercerising is produced by tension and was discovered by Horace Lowe in 1889.


Process

Treatment with sodium hydroxide destroys the spiral form of the cellulose with formation of
alkali cellulose In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a s ...
, which is changed to
cellulose hydrate Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wa ...
on washing out the alkali. Caustic soda concentrations of 20–26% are used. Effective mercerization requires the use of
wetting agent Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming ...
s. The improved lustre of mercerised cotton is due to the production of nearly circular cotton fibres under tension. Another characteristic feature is the untwisting (deconvolution) of the cotton hair. In dry mercerization, the process is carried out while drying the fabric on a
stenter A stenter (sometimes called a tenter) is a specialist oven used in the textile industry for drying and heat treating fabric after wet processing. It consists of heated chambers, adjustable to the width of the fabric being treated. Fabric is fed ...
.


References


External links

* {{fabric Fibers Cotton Textile treatments 1844 introductions