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DYEING. By... Vasant Kothari. Dyeing Definition. Coloring of Textile Material is called as Dyeing
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DYEING By... Vasant Kothari www.vasantkothari.com
Dyeing Definition • Coloring of Textile Material is called as Dyeing • Coloration of Dyeing involves the use of Dye Stuff which are capable of reacting and combing with the Textile fiber molecule, usually when in a water solution, and usually with other auxiliary chemicals to enhance the process. • Depth of Shade: The Darkness or Lightness of Color in Dyeing is known as the depth of the shade, this depend on the quantity of the Dye used in the ratio to the fiber weight. www.vasantkothari.com
Dye Definition • Colorant which is homogeneously dispersed in the dye medium • Usually soluble • Naturally occurring or synthetic organics • Categorized by... 1. Method of Application 2. Chemical Structure • The application of color to the whole body of a textile material with Some degree of fastness. www.vasantkothari.com
Principle of Dyeing • The Textile material is moved in a solution of a Dye, then the dye is attracted to the material and it is seen that the dye liquor gradually looses its color whilst the Textile material becomes more deeply Dyed. www.vasantkothari.com
Dye Expectations • Dyeing is a craft, not a pure science, and like all crafts there is a learning curve and many nuances that affect the outcome... • The color, evenness (or lack thereof) and total effect produced depends on several factors that you control: the amount of dye used, ... the temperature of the water of the dye bath,… the fabric, whether pre-washed or not,… particular water chemistry, the type of fabric, does the fabric have any treatments on it, time for the process, etc., etc. www.vasantkothari.com
Dye Expectations • The color and evenness depends on the factors above and more, most of which you can control, some of which you cannot. Colors also can vary from dyelot to dyelot because the pure primary colors used for mixing can vary a little from the original manufacturer, which can affect the mixes made with them. • To repeat a color exactly, you need to use the same dyelot, and you need to do everything exactly the same as you first did it. www.vasantkothari.com
Objectives Of Dyeing • Shade • Fastness Properties • Cost www.vasantkothari.com
Keys To Good Quality • Consistency • Uniformity • Knits - Low Tension • Woven - Penetration www.vasantkothari.com
Types Of Dyeing Systems • Aqueous - in water • Non-aqueous - in organic solvents • Sublimation - thermosol, heat transfer www.vasantkothari.com
Types of Fibers • Hydrophilic Fibers Cotton, Rayon, Wool, Silk, etc.. • Hydrophobic Fibers Acetate, Polyesters, Polyamides, etc… www.vasantkothari.com
Basic Steps In Dyeing • Dissolve or Disperse dye • Diffuse the dye to the surface of the fiber • Adsorb the dye "onto" the fiber surface • Diffuse dye "into" the fiber www.vasantkothari.com
Causes Of Non-Level Dyeing • Too little agitation • Too low liquor ratio • Rate of dyeing too high • Uneven pick-up in padding • Uneven moisture penetration • Migration during drying • Chemical or mechanical bard in the fabric • Dyebath Instability • Construction www.vasantkothari.com
Factors In Selecting Dyes • Economy • Shade (brightness or dullness) • Fastness Requirements • Level Dyeing Properties • Barre Control • Ease of Dispersed Dissolving • Dusting • Environmental Concerns www.vasantkothari.com
Dyes for Cellulose Fibers • These are your choices if you want to dye a t-shirt. Cellulose fibers include cotton, linen, rayon, hemp, ramie, and tencel. • Fiber Reactive Dyes (best choice) • Direct Dye (hot water dye, less washfast) • Vat Dyes (more complex method) • Naphthol dyes (more hazardous, less available) • All purpose Dye (hot water dye, less washfast) www.vasantkothari.com
Dyes for Protein Fibers • Protein fibers include all fibers made by animals: wool, angora, mohair, cashmere, as well as silk. Silk is the only non-hair animal fiber, and can be dyed like wool or like cellulose fibers, above. The high-pH recipes used for most cellulose dyes will ruin animal hair fibers. • Dyes that can be used for protein fibers include the following: • Acid dyes • Reactive dyes used as acid dyes • Natural dyes (these work better on wool than on cotton) • Vat Dyes www.vasantkothari.com
Dyes for Synthetic Fibers • Polyester requires the use of disperse dyes. • Nylon, which is a truly synthetic fiber, happens to dye quite well with the same acid dyes that work on wool and other animal fibers. Nylon can also be colored with a type of fabric paint called 'Pigment dye'. • Acetate, also known as rayon acetate, requires the use of disperse dye. • Acrylic can be dyed with disperse dyes or with basic dyes. www.vasantkothari.com
Dyeing blends • Most cotton/polyester blends are best dyed as for cotton, using fiber reactive dyes, leaving the polyester undyed. Cotton/nylon blends may be dyed with all-purpose dye, first with soda ash at room temperature to dye the cotton, then in hot water with vinegar to dye the nylon. www.vasantkothari.com
Direct dyes: used for cotton, linen, regenerated cellulose fibers, and some synthetics • Mordant dyes: wool, silk and nylon • Sulphur dyes: cotton • Vat dyes: cotton and cellulose fibers • Soluble vat dyes : cotton, viscose rayon, wool, and silk • Basic dyes: wool, slik and other protein fibers, and some synthetics • Dispersed dyes: acetate and some other synthetics • Azoic dyes: cotton and viscose rayon, acetate and some other synthetics, and silk • Acid dyes: wool, silk, and some synthetics www.vasantkothari.com
Direct Dyes • Direct dyes are a class of dyes for use on cellulose fibers, such as cotton. • The colors of most direct dyes are duller than those provided by fiber reactive dyes, and the wash fastness is poor. • One small advantage is that direct dyes are, in just a few cases, a little more lightfast, that is, resistant to fading in the light, than a few of the fiber reactive dyes. • Without an appropriate after-treatment, direct dyes bleed a little with every washing, losing their brightness and endangering other clothes washed in the same load. www.vasantkothari.com
Disperse Dyes • These dyes derive their names from their insoluble aqueous properties and the need to apply them from an aqueous dispersion. • Polyester requires the use of disperse dyes. • Disperse dyes on fabric are more likely to cause allergies than other textiles dyes. • Wash Fastness varies with the fibers. • Fastness to Crocking is Good to Excellent. • Light Fastness is Fair to Good. www.vasantkothari.com
Acid Dyes • Acid dyes are water soluble anionic dyes which are applied to fibers such as silk, wool, nylon & modified acrylic fibers from neutral to acid dye baths. • Bright Colors. • Most are non fast to washing. • Excellent Fastness to Dry Cleaning. www.vasantkothari.com
Azoic Dyes • Azoic dyes are so called because their molecule contain an Azo group. • It is suitable for Man Made and Natural Cellulose fibers such as Cotton, Viscose, etc. • Bright Shades, mostly deep Red, Yellow, Orange, etc. • Light Fastness Fair to Good. • Washing Fastness Good to Excellent. • Heavy shades may have poor fastness to Crocking. www.vasantkothari.com
Reactive Dyes • Reactive Dyes are so called because their molecules react chemically with the fiber polymers to form a covalent bond. • The dyestuff thus becomes a part of the fibre and is much less likely to be removed by washing than are dyestuffs that adhere by adsorption. • Suitable for Man made and Natural Cellulose Fibers, Synthetic Fiber and Natural Protein Fiber. • Difficult dye with which to attain close shade matching. • Bright Shades. • Generally good to excellent fastness to light & washing. www.vasantkothari.com
Sulphur Dyes • These dyes contain Sulphur atom in their molecules. • Sulphur dyes are insoluble in water • Suitable for the Man Made and Natural Cellulosic fibers • Dull Shades, predominantly navy, black, brown • Excellent Fastness to Light and Washing • Relatively Low cost for Dark colors. www.vasantkothari.com
Vat Dyes • Vat dyeing" means dyeing in a bucket or vat. • Vat dyes are insoluble in water and incapable of dyeing fibers directly. • Both cotton and wool, as well as other fibers, can be dyed with vat dyes • Vat dyes have excellent wash and light fastness properties. • It is usually very bright and will hold up better when bleached than most other dyes. www.vasantkothari.com
Solvent Dyes • Solvent dye is a dye which is soluble in an organic solvent and is mostly introduced in the form of a solution in an organic solvent. • It is very expensive method. • It’s a alternative method as the use of water and its disposal in a non polluting form has become more expensive. • Still it is relatively untied and uneconomical as compared to conventional dyeing techniques. www.vasantkothari.com
Basic Dyes • Basic dyes ('basic' as in the opposite of acidic, not as in 'back to basics') are said to be very bright, and particularly washfast on acrylic. • Basic dyes can be used to dye wool or cotton, but they do not perform well, tending to fade in sunlight quite badly. • Characterized by Brilliance and Intense hue. • Very Poor fastness to washing for Cellulosic and Protein • Excellent fastness to light. www.vasantkothari.com
Pigment Dyes • Pigments are colored organic materials in the form of insoluble powders, which are mixed with various resins, solvents and additives to manufacture plastics, rubbers & allied products. • The pigment lays on the surface and becomes part of the dry film. • Heavy Shade tends to stiffen fabric. • Mostly excellent fastness to light. www.vasantkothari.com
Mordant Dyes • Mordant dyes are those dyes which require a mordant in their application and which upon combination with the mordant deposit insoluble color on the substrate, e.g., dyes with metal chelating groups. • The mordant substances include such acids as tannic acid, sumac, gall nuts, bark extracts, oleic and stearic acids, and Turkey red oil; and metallic substances such as various combinations or soluble salts of chromium, aluminum, iron, copper, and tin. • Suitable for Wool • Relatively Dull Colors • Good to Excellent Fastness to Light and Wash. www.vasantkothari.com
Natural Dyes • Natural dyes are, in most cases, acid dyes, which is why they will bond to wool and other animal fibers, but not to cotton. A way to improve attachment to wool, and to make some weak attachment to cotton possible, is to use metal ions, sometimes including toxic heavy metal ions, to form a bridge between the dye and the fiber; this is called mordanting. Cotton is typically mordanted with tannins in addition to metal ions Indigo is a natural dye, but it is quite different from other natural dyes, in that it is a member (the very first member) of the class of dye known as vat dyes, see above. www.vasantkothari.com
Textile Material may be dyed as… • Fiber …… Stock Dyeing and Top Dyeing • Yarn …... Skein, Package and Beam Dyeing • Fabric ……Winch, Jet, Jig, Aerodynamic, Pad & Beam • Garment …… Paddle www.vasantkothari.com
Stock Dyeing • It refers to the dyeing of fibers, or stock, before it is spun into yarn. • It is done by putting loose, unspun fibers into large vats containing the dye solutions, which are heated to proper temperature. • 500 to 3000 pounds of fiber are dyed at one time. • Usually result in excellent penetration of the dye into fiber and evenness of color throughout. www.vasantkothari.com
Stock Dyeing • There is 10-15% Waste of dyed fiber through subsequent manufacturing of Spinning and Weaving. • There is a strong element of Fashion risk in stock dyeing because as to the final color of a fabric has to be made at the earliest stage in its manufacturing. • It produces soft, heather like color effect. • Production is relatively Low. • It is most costly method for dyeing. www.vasantkothari.com
Top Dyeing • Top dyeing is also the dyeing of fiber. • The term TOP refers to fibers of Wool from which shorter fibers have been removed, thus it select long fibers. • The top in the form of Sliver is dyed, then later blended with the other colors of dyed top to produce desired blended heather shades. • It would be waste of money if all the fibers, both the short and long, were dyed before being made into sliver. www.vasantkothari.com
Skein Dyeing • It consists of immersing large, loosely wound hank of yarn. • Soft, lofty yarns, such as hand knitting yarns, are usually skein dyed. • Skein dyeing is the most costly yarn dyed method. www.vasantkothari.com
Package Dyeing • In this about a pound of yarn is wound on a small perforated spool or tube called package. www.vasantkothari.com
Beam Dyeing • Beam Dyeing is simply a much larger version of package dyeing. • An entire warp beam is wound onto a perforated cylinder, which is then placed in the beam dyeing machine where the flow of the dye bath alternates as in package dyeing. • Beam dyeing is more economical than Skein and Package dyeing. www.vasantkothari.com
Winch Dyeing • Also know as Beck Dyeing or Box Dyeing. • The fabric, in a rope like form, is dyed in a relaxed condition (without tension). • It retains much of its original softness of hand and fabric fullness. • Widely used for Knitted fabrics, woolen and worsted woven cloths. • Capacity of around 1000 yds www.vasantkothari.com
Jet Dyeing • In this the fabric is being dyed is circulated through the dyeing machine on a jet flow of a dye bath. • Compared to Winch dyeing uses much less water, energy and chemical, and has shorter dyeing cycle time. • The capacity is around 1400 lbs of material. www.vasantkothari.com
Jet Dyeing www.vasantkothari.com
Jig Dyeing • It involves treating the fabric in open width. • The fabric is not passed through the dye bath but rather passed through the dye bath. • Upon completion of the first pass, the fabric reverses and is passed again through the dye bath. • It places the certain degree of tension. • It is more economical. • Chances of shade variation are there due to variation in tension. www.vasantkothari.com
Pad Dyeing • In this, fabric in open width first passed through the dye bath, then through rollers where the dye solution is squeezed into the fabric. • Pad Dyeing places the tension on the fabric. • Pigment may be applied to achieve solid color fabric. • It is continuous dye system where quantities of fabric are run continuously run through a pad, then into heat steam chambers, then into washers, rinsers and dry and finally emerging as completely dyed fabric. www.vasantkothari.com
Beam Dyeing • It is practically identical beam dyeing used for yarns. • Used to dye fabrics of light weight, open construction. • Tricot is a typical type which is dyed on Beam Dyeing. • It is rapid and economical. • Beam Dyed fabric is not subject to the stresses and tensions. • 10000 yds or 4000 lbs of fabric could be wound on the beam. www.vasantkothari.com
Aerodynamic Dyeing • The fabric transport takes place by means of a separate gas circuit through humid air or through an air-steam-mixture so that also an injection-free transport, i.e. a fabric passage without liquor is possible. i.e. the fabric is constantly moved from loading to the batch end, also during the discharge and filling processes. • Dyestuffs, chemicals and auxiliaries are dissolved in the processing liquor and injected directly into an air stream. • In such a way, the liquor is atomized and evenly distributed on the surface of the textile material. The penetration of the fibers and consequently, the liquor exchange in the textile material are optimal. www.vasantkothari.com
