Monday, December 28, 2015

What is Dyeing?Some of the major dyeing processes

DYEING: A process of coloring fibers, yarns, or fabrics with either natural or synthetic dyes.Or Dyeing  is a processes  or combination of processes which is performed to give a reasonably permanent coloration to textile fabric.
            
Some of the major dyeing processes are described below:

Batik:  A resist-dyeing process in which portions of a fabric are coated with wax; during the dyeing process, only the uncovered areas take up dye. The process can be repeated so that several colors are used. Batik dyeing is often imitated in machine printing.

Chain Dyeing:  A method of dyeing yarns and fabrics of low tensile strength of tying them endto- end and running them through the dyebath in a continuous process.

Cross Dyeing:  A method of dyeing blend or combination fabrics to two or more shades by the use of dyes with different affinities for the different fibers.

High-Temperature Dyeing:  A dyeing operation in which the aqueous dyebaths are maintained at temperatures greater than 100°C by use of pressurized equipment. Used for many manufactured fibers.

Ingrain:  Term used to describe yarn or stock that is dyed in two or more shades prior to knitting or weaving to create blended color effects in fabrics.

Jet Dyeing:  High temperature piece dyeing in which the dye liquor is circulated via a Venturi jet thus providing the driving force to move the loop of fabric.

Mass-Colored:  A term to describe a manufactured fiber (yarn, staple, or tow) that has been colored by the introduction of pigments or insoluble dyes into the polymer melt or spinning solution prior to extrusion. Usually, the colors are fast to most destructive agents.

Muff Dyeing: A form of yarn dyeing in which the cone has been removed.

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.

Pad Dyeing:  A form of dyeing whereby a dye solution is applied by means of a padder or mangle.

Piece Dyeing:  The dyeing of fabrics “in the piece,” i.e., in fabric form after weaving or knitting as opposed to dyeing in the form of yarn or stock.

Pressure Dyeing:  Dyeing by means of forced circulation of dye through packages of fiber, yarn, or fabric under superatmospheric pressure.

Reserve Dyeing:  1. A method of dyeing in which one component of a blend or combination fabric is left undyed. The objective is accomplished by the use of dyes that have affinity for the fiber to be colored but not for the fiber to be reserved.  2. A method of treating yarn or fabric so that in the subsequent dyeing operation the treated portion will not be dyed.

Short-Liquor Dyeing:  A term used to describe any yarn or piece dyeing in which the liquor ration has been significantly reduced. The technique was designed to save water and energy
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.

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.

Solvent Dyeing:  A dyeing method based on solubility of a dye in some liquid other than water, although water may be present in the dyebath.

Space Dyeing:  A yarn-dyeing process in which each strand is dyed with more that one color at irregular intervals. Space dyeing produces an effect of unorganized design in subsequent fabric form. The two primary methods are knit-de-knit and warp printing.

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.

Thermal Fixation:  A process for dyeing polyester whereby the color is diffused into the fiber by means of dry heat.

Union Dyeing:  A method of dyeing a fabric containing two or more fibers or yarns to the same shade so as to achieve the appearance of a solid colored fabric.

Yarn Dyeing:  Yarn dyeing is nothing more than adding color to the yarn that has been used to create a garment or item, or adding color to yarn that will soon be used in knitting or crocheting projects. Yarn can be dyed in the form of skeins, muff, packages, cheeses, cakes, chain-wraps, and beams.