Mercerisation is atextile finishing treatment forcellulosefabric andyarn, mainlycotton andflax, which improvesdye uptake andtear strength, reducesfabric shrinkage, and imparts asilk-likeluster.
The process was devised in 1844 byJohn Mercer,[1] who treated cotton with solutions of 20–30%sodium hydroxide 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 termedfulled cotton, a nod to the process offulling in woven wool fabric. Mercer regarded the increased affinity for dyes as the most important technical aspect. Mercer also experimented withsulfuric acid andzinc chloride solutions and discovered theparchmentising effect of sulfuric acid.[2]
The silk-like lustre now commonly associated with mercerising is produced by tension and was discovered byHorace Lowe in 1889.[1]
Treatment with sodium hydroxide destroys the spiral form of the cellulose with formation ofalkali cellulose, which is changed tocellulose hydrate on washing out the alkali. Caustic soda concentrations of 20–26% are used. Effective mercerization requires the use ofwetting agents.[3]
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 astenter.