Scouring Process in Textile | How to Scouring Textile Fabric | AlkalineEnzyme Scouring of Cotton Textiles

Yarns and fabrics may be dirty, contain natural waxes or oils, or have been treated with size or lubricants used in spinning, weaving or knitting. These can all interfere with dyeing, often leading to non-level results. Scouring is a large topic, and the process used depends on the fibre type and its condition. “True” scouring of greige cellulosic fabrics is typically done, after desizing, at the boil or at higher temperature in pressure vessels, with as much as 10 grams sodium hydroxide per litre of water, plus surfactants, and the process may last for several hours. Commercial scouring of wool may use solvents, similar to dry cleaning, as part of the process. White fabrics sold at retail have normally be scoured at the mill; “natural” fabrics usually have not (some “natural” fabrics have been scoured but not bleached).

Art dyeing literature often refers to what amounts to laundering as scouring. This is inadequate for greige fabrics, but often quite acceptable for “white goods”. A long machine wash with the hottest water possible, about a gram of soda ash per litre of water (about a teaspoon per gallon) and some (preferably optical brightener free) detergent, followed by two rinses is usually acceptable. Sodium hexametaphosphate may be helpful if the water is hard. Woven white cottons often contain starch that will not be removed by such a limited process.

Alkaline Enzyme Scouring of Cotton Textiles
The invention relates to a process for treatment of cellulosic material, as for example, knitted or woven cotton fabric, comprising the steps of preparing an aqueous enzyme solution comprising pectinase, treating the cellulosic material with an effective amount of the aqueous enzyme solution under alkaline scouring conditions; e.g., pH of 9 or above and a temperature of 50° C. or above, in a low calcium or calcium-free environment, yielding a modification of the cellulosic material such that exhibits an enhanced respond to a subsequent chemical treatment.

Traditionally, cotton scouring has required the use of harsh alkaline chemicals (caustic), extreme temperatures and large volumes of water. Expenses include not only the cost of the caustic and energy, but also the cost of treating waste water to remove residual caustic and by-products.

Today, textile producers have a new, effective alternative to chemical scouring with the advent of the Cottonase™ enzyme. This novel enzyme not only cleans better than chemical scouring, but also greatly reduces the need for extensive waste water treatment and energy consumption. The Cottonase™ enzyme is a versatile, economically viable and environmentally friendly alternative to chemical scouring in cotton preparation.

How to Scouring Textile Fabric:

1. Simply wash your fabric, this includes PFD fabric, in the washing machine in hot water with Soda Ash. Do not add any fabric softeners to the wash. If you must dry your fabric do so without any fabric softener sheets
2. Using an large enamel or stainless steel pot, fill the pot at least half full and place one ounce of soda ash into the pot per pound of cotton or linen fabric/fiber.
3. Place fabric into water, swish it around using a stainless steel spoon.
4. Bring water to a boil!!!
5. Adjust heat to a low boil/hard simmer and allow to boil for two hours. stir the fabric every 15 minutes or so t make sure that the fabric is being adequately scoured
6. After two hours remove from heat source, allow fabric to cool down until the fabric is at room temperature. 
7. Remove the fabric from the water and rinse.

Scouring Treatments of Cotton, Silk, Wool and Synthetics Materials

Natural fibers contain oils, fats, waxes, minerals, leafy matter and motes as impurities that interfere with dyeing and finishing. Synthetic fibers contain producer spin finishes, coning oils and/or knitting oils, Mill grease used to lubricate processing equipment, mill dirt, temporary fabric markings and the like may contaminate fabrics as they are being produced.

The process of removing these impurities is called Scouring. Even though these impurities are not soluble in water, they can be removed by Extraction, dissolving the impurities in organic solvents, Emulsification, forming stable suspensions of the impurities in water and Saponification, Converting the contaminates into water soluble components.

Scouring is usually carried out by means of continuous or discontinuous systems, with the same machines used for downstream treatments; temperature, processing time, pH, concentration of reagents, depend on the fibre,whiteness required and on the machine used.Incomplete scouring processes usually originate dyeing and printing defects due to different degrees of wettability and to inconsistent affinity for dyes of the material.

Types of Scouring Treatments
1.Scouring By Chemicals Means
2.Bio scouring or scouring with Enzymes

Scouring of Cotton
In the scouring process the cotton cellulose material is treated with a solution containing alkali ( soda ash and caustic soda), an anionic and/or nonionic detergent, a wetting agent, a complexing and sequestering for the removal of metal ions and polyacrylates or polyphosphonates as special surfactant free dispersing agents, at high temperature.

The scouring operation was conventionally done in kier machines and hence the process was called kier boiling , but now a days the scouring is done mostly in the dyeing machines itself as a part of combined or single operation such as scouring and bleaching.

I. Saponification of fats into water soluble soap and water miscible glycerin under alkaline conditions.
II. Hydrolysis of proteins into water soluble degradation products.
III. Dissolution of amino compounds.
IV. Solubilising of pectose and pectins by converting into soluble salts .
V. dissolution and extraction of mineral matter.
VI. Emulsification and solubilisation of natural oils and waxes.
VII. removal and dispersion of dirt particles and kitty by the action of alkali and detergent.

The material after scouring is more absorbent , free from natural impurities and coloring matter.This treatment can be carried out on filaments, yarns and fabrics.

Scouring of Silk
The scouring of pure silk is a degumming process used to remove sericin (silk gum) from fibroin floss. Sericin is the gummy element which keeps together the fibroin floss and gives the silk a hard hand and dull appearance. It is carried out on yarn, on dyed yarn, piece-dyed fabric or on products ready for printing. The treatment, which causes a loss of weight ranging between 24 and 28%, gives the degummed silk a lustrous appearance and a soft hand; the treatment is carried out with soapy solutions or with buffer dissolving agents. It is also possible to use enzymes (protease), which hydrolyses sericin.

Scouring of Wool
On wool, the scouring process removes oils and contaminants accumulated during upstream processing steps and can be carried out on slivers, yarns and fabrics with solutions containing sodium carbonate with soap or ammonia, or anionic and non-ionic surfactants, which carry out a softer washing to avoid any damage to the fibres.

Scouring of Synthetics
The scouring process applied to synthetic fibres removes oils, lubricants and anti-static substances, dust, contaminants and can be carried out on yarns and fabrics (when warp yarns have been bonded, the treatment is called debonding). It is carried out by means of surfactants, detergents and emulsifying agents.