[2] The wet process is usually done in the manufactured assembly of interlacing fibers, filaments and yarns, having a substantial surface (planar) area in relation to its thickness, and adequate mechanical strength giving it a cohesive structure.
The textile industry uses a large amount of water in its varied processes especially in wet operations such as pre-treatment, dyeing, and printing.
Recently, some companies have started harvesting rainwater for use in wet processes as it is less likely to cause the problems associated with water hardness.
Textile mills including carpet manufacturers, generate wastewater from a wide variety of processes, including wool cleaning and finishing, yarn manufacturing and fabric finishing (such as bleaching, dyeing, resin treatment, waterproofing and retardant flameproofing).
Pollutants generated by textile mills include BOD, SS, oil and grease, sulfide, phenols, and chromium.
Following treatment with polymer-based flocculants and settling agents, typical monitoring parameters include BOD, COD, color (ADMI), sulfide, oil and grease, phenol, TSS and heavy metals (chromium, zinc, lead, copper).
In the textile industry, wet process engineering plays a vital role in the area of pre-treatment, dyeing, printing, and finishing of both fabrics and apparel.
When done to fabrics containing cotton, this results in increased water affinity, better dyeing characteristics, improved reflection, no "frosty" appearance, a smoother surface, better clarity in printing, improved visibility of the fabric structure, less pilling and decreased contamination through the removal of fluff and lint.
But in case of knit fabric, similar process of singeing is known as bio-polishing where enzyme is used to remove the protruding fibers.
Desizing is the process of removing sizing materials from the fabric, which is applied in order to increase the strength of the yarn which can withstand with the friction of loom.
Fabric which has not been desized is very stiff and causes difficulty in its treatment with a different solution in subsequent processes.
Scouring is a chemical washing process carried out on cotton fabric to remove natural wax and non-fibrous impurities (e.g.
A kier is usually enclosed, so the solution of sodium hydroxide can be boiled under pressure, excluding oxygen which would degrade the cellulose in the fiber.
Another scouring chemical is a detergent which is an emulsifying agent and removes dust and dirt particles from the fabric.
Due to this, and in order to reduce the alkali content in the effluent, Bio-scouring is introduced in the scouring process in which biological agent is used, such as an enzyme.
After scouring and bleaching, optical brightening agents (OBA), are applied to make the textile material appear more white.
Dye molecules are fixed to the fiber by absorption, diffusion, or bonding with temperature and time being key controlling factors.
Because the color pigments become a part of the fiber, solution dyed materials have excellent colorfastness to light, washing, crocking (rubbing), perspiration, and bleach.
Many t-shirts, sweaters, and other types of casual clothing are product dyed for maximum response to fashion's demand for certain popular colors.
However, reduction in alkaline liquor produces the water-soluble alkali metal salt of the dye, which, in this leuco form, has an affinity for the textile fiber.
Reactive dyes utilize a chromophore attached to a substituent that is capable of directly reacting with the fiber substrate.
The very fine particle size gives a large surface area that aids dissolution to allow uptake by the fiber.
With suitable adjustment of dyebath conditions the two components react to produce the required insoluble azo dye.
The initial bath imparts a yellow or pale chartreuse color, This is after–treated with a sulfur compound in place to produce the dark black we are familiar with in socks for instance.
In printing, wooden blocks, stencils, engraved plates, rollers, or silkscreens can be used to place colors on the fabric.
Textile finishing is the term used for a series of processes to which all bleached, dyed, printed, and certain grey fabrics are subjected before they put on the market.
An ordinary calender consists of a series of hard and soft (resilient) bowls (rollers) placed in a definite order.
The process of raising consists of lifting from the body of the fabric a layer of fibers which stands out from the surface which is termed as "pile".
The formation of the pile on a fabric results in a "lofty" handle and may also subdue the weave or pattern and color of the cloth.
Thus softening and smoothing agents are applied not only to improve the handle but also to compensate as much as possible for losses in tear strength and abrasion resistance.