Dyeing Different Methods,Application and Its Types
What is Dyeing:
Dyeing is the application of dyes or pigments on textile materials such as fibers, yarns, and fabrics with the goal of achieving color with desired color fastness. Dyeing is normally done in a special solution containing dyes and particular chemical material.
There are two different methods to transfer the dye from the liquor to the fibre:
In exhaust dyeing, a finite amount of textile materials (in the form of fibers, yarn or fabric) is placed in the dye liquor and remains in its contact throughout the dyeing time, during which the dye molecules gradually move (or exhaust) from the liquor toward the fabric, for absorption and fixation in the textile material. The rate of dye exhaustion, absorption and fixation are controlled with the help of dyeing temperature, liquor agitation, PH or auxiliaries such as electrolytes, alkalis, leveling agents or retarding agents.
This process is carried out using mechanical means (pad-batch wetting). The dyeing liquor is distributed homogeneously onto the fabric (i.e. also the dye is distributed homogeneously). In a second stage, the dye penetrates into the fabric and is then fixed. At the end of the process, the material is washed.
Some operations must be carried out for both exhaust and pad dyeing
- Dissolve or disperse the dye in water and filter.
- Achieve a homogeneous contact between the dyeing liquor and the fibre.
- Make the dye penetrate into the fibre.
- Fix the dye in the core of the fibre.
- Final washing.
Types of Dyeing:
Eco dyeing is a natural dyeing method in which fabric is dyed with the help of leaves – it is almost like printing in that the dye from plants appears as prints. In this method, plants and flowers are placed on top of fabric, in a single layer or stacked on top of each other and then steamed or immersed in hot water. This process extracts the pigments on the leaves to the fabric and creates a print on the fabric. This method results in a contact print in the shape of the leaf or flower used.
In fiber dyeing, the dyeing takes place at the fiber stage before they are spun into yarn. It is also called stock dyeing. Examples are melanges and medleys.
In yarn dyeing, the yarns are dyed first before the fabric manufacturing stage. The yarn dyeing happens in hanks or in package dyeing. Package dyeing is a method where yarns are wound on perforated cones placed in a dye vessel. The dye solution is then alternatively pushed inside out and vice versa. Examples are many stripes, patterned (checks) and jacquard designed fabrics.
The dyeing of cloth after it is being woven or knitted is known as piece dyeing. It is the most common methods of dyeing used. The various methods used for this type of dyeing include jet dyeing, Jig dyeing, pad dyeing and beam dyeing.
Garment dyeing is the dyeing of the completed garments. The types of apparel that can be dyed are mostly non-tailored and simpler forms, such as sweaters, sweatshirts, T-shirts, hosiery, and pantyhose. The effect on sizing, thread, zippers, trims and snaps must be considered. Tailored items, such as suits or dresses, cannot be dyed as garments because the difference in shrinkage of the various components and linings disort and misshape the article.
It is used for dyeing long yards of fabric. The fabric is passed in rope form through the dye bath. This rope of the fabric moves over a rail on to a reel which immerses it into the dye and then draws the fabric up and forward and brings it to the front of the machine. This process is repeated many times until the desired color intensity is obtained.
The dyeing of a textile fibre is carried out in a solution, generally aqueous, known as the dye liquor or dye bath. For true dyeing (as opposed to mere staining) to have taken place, the coloration must be relatively permanent—that is, not readily removed by rinsing in water or by normal washing procedures. Moreover, the dyeing must not fade rapidly on exposure to light. The process of attachment of the dye molecule to the fibre is one of absorption; that is, the dye molecules concentrate on the fibre surface.
In any dyeing process, whatever the chemical class of dye being used, heat must be supplied to the dye bath energy is used in transferring dye molecules from the solution to the fibre as well as in swelling the fibre to render it more receptive. The technical term for the transfer process is exhaustion. Evenness of dyeing, known as levelness, is an important quality in the dyeing of all forms of natural and synthetic fibre. It may be attained by control of dyeing conditions—that is, by agitation to ensure proper contact between dye liquor and substance being dyed and by use of restraining agents to control rate of dyeing, or strike.
Dyes are generally used in combination to achieve a desired hue or fashion shade. If the substance to be dyed consists of only one type of fibre, such as wool, the dye mixture will be made up solely of wool dyes. But if the fabric contains more than one kind of fibre and they differ in dyeing properties, then mixtures of different application classes of dyes are used.
There are different dye classes available for dyeing fibers. It all depends on what are your customer’s fastness requirements, as well as being cost conscious. Types and application of dyes that can be used when dyeing fabric.