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Dyeing

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Textile Dyeing Methods-Dyeing is a method which imparts beauty to the textile by applying various colors and their shades on to a fabric. Dyeing can be done at any stage of the manufacturing of textile- fiber, yarn, fabric or a finished textile product including garments and apparels.

 

Dyeing Methods

You May Read: What is Dyeing in textiles 

Color is applied to fabric by different methods and at different stages of the textile manufacturing process.

Stock dyeing: The fiber is dyed even before it is spun.

Top dyeing: Top is the combed wool. In this method, the fiber is dyed in the stage just before the appearance of the finished yarn.

Piece dyeing: In this method, small batches of constructed natural colored fabric are dyed according to the demands for a given color.

Solution pigmenting or dope dyeing: Dye is added to the solution before it is extruded through the spinnerets for making synthetic filaments.

Garment dyeing: Garment dyeing Dye is applied to finished products such as apparel and garments.

Stock dyeing: 

Stock dyeing is used to dye fibers. In this process, the staple fibers are packed into a vessel and then dye liquid is forced through them. Although the dye solution is pumped in large quantities, the dye may not penetrate completely into the fibers and some areas may be left without dyeing. However, the following blending and spinning processes mix up the fibers in such a thorough way that it results in an overall even color. Woolens are usually stock dyed.

Top dyeing: Top is the combed wool sliver. It is wound on perforated spools and the dye solution is circulated through it. This method results in very even dyeing.

Yarn dyeing: In this process, the staple fibers are packed into a vessel and then dye liquid is forced through them. Although the dye solution is pumped in large quantities, the dye may not penetrate completely into the fibers and some areas may be left without dyeing. However, the following blending and spinning processes mix up the fibers in such a thorough way that it results in an overall even color. Woolens are usually stock dyed.

When dyeing is done after the fiber has been spun into yarn, it is called yarn dyeing. In this method, the dyestuff penetrates the fibers to the core of the yarn. There are many forms of yarn dyeing- Skein (Hank) Dyeing, Package Dyeing, Warp-beam Dyeing, and Space Dyeing.

Skein (Hank) Dyeing:  The yarns are loosely arranged in skeins or coils. These are then hung over a rung and immersed in a dyebath in a large container. In this method, the colour penetration is the best and the yarns retain a softer, loftier feel. It is mostly used for bulky acrylic and wool yarns.

 

Textile Dyeing methods

 

Package Dyeing: The yarns are wound on spools, cones or similar units and these packages of yarn are stacked on perforated rods in a rack and then immersed in a tank. In the tank, the dye is forced outward from the rods under pressure through the spools and then back to the packages towards the center to penetrate the entire yarn as thoroughly as possible. Mostly, the carded and combed cotton which are used for knitted outerwear is dyed through this method.

Warp-beam Dyeing: It is similar to package dyeing but more economical. Here, the yarn is wound on to a perforated warp beam and then immersed in a tank for dyeing it applying pressure.

Space Dyeing: 

In this method, the yarn is dyed at intervals along its length. For these two procedures- knit- deknit method and OPI Space-Dye Applicator- are adopted. In the first method, the yarn is knitted on either a circular or flat-bed knitting machine and the knitted cloth is then dyed and subsequently it is deknitted. Since the dye does not readily penetrate the areas of the yarn where it crosses itself, alternated dyed and undyed spaces appear. The OPI Space-Dye Applicator technique produces multi coloured space- dyed yarns. The yarns are dyed intermittently as they run at very high speeds through spaced dyebaths. They are continuously subjected to shock waves produced by compressed air having supersonic velocities.

Piece Dyeing: The constructed fabrics are piece dyed for the flexibility they provide. The textile manufacturer can dye the whole fabric in batches according to the fashion demands of the time thus avoiding wastage and resultantly loss. There are several methods prevalent or piece dyeing.

Beck dyeing: It is used for dyeing long yards of fabric. The fabric is passed in rope form through the dyebath. This rope of the fabric moves over a rail onto 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.

Jig dyeing: It is similar to the process of beck dyeing with a slight variation. The fabric in jig dyeing is held on rollers at full width rather than in rope form as it is passed through the dyebath.

Pad dyeing:

 Padding is also done while holding the fabric at full width. The fabric is passed through a trough having dye in it. Then it is passed between two heavy rollers which force the dye into the cloth and squeeze out the excess dye. Then it is passed through a heat chamber for letting the dye to set. After that it is passed through washer, rinser and dryer for completing the process.

Jet dyeing: Fabric is placed in a heated tube where jets of dye solution are forced through it at high pressures. The fabric too moves along the tube. The solution moves faster than the cloth while coloring it thoroughly.

Solution pigmenting or dope dyeing: This is a method applied for dyeing the synthetic fibers. Dye is added to the solution before it is extruded through the spinnerets for making synthetic filaments. This gives a colorfast fiber as the pigments are used which are the fastest known colors.

Garment dyeing: When the finished textile product such as hosiery or sweaters are dyed, it is called garment dyeing. A number of garments are packed loosely in a nylon net and put into a dyestuff filled tub with a motor driven paddle. The dye is thrown upon the garments by the moving paddles’ effect.

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References: textile focus