Names of Different Dyes
And Their Application
The dye used depends on the type of material and the specific requirements to be met. For some purposes, high light fastness is essential; but for others it may be inconsequential. Factors considered in dye selection include fastness to light, reaction to washing and rubbing (crocking), and the cost of the dyeing process.
Effective preparation of the material for dyeing is essential.
What are Dyes?
Dyes may be defined as the different types of colouring particles, differ each type from other type in chemical composition and are used for colouring fabrics, yarns in different fine of colors and shades and which are completely soluble in liquid substance. They are colored organic compounds that are used to impart color to various substrates.
Dyes are widely applied on paper, leather, fur, hair, drugs, cosmetics, waxes, greases, plastics and textile materials.
Soluble chemicals that contain chromophores, or color-containing compounds. Dyes are mixed with other additives in a color solution. They can be derived from natural sources, such as plants, but are more commonly human made. Different classes of dyes are used for different fibers and stages of the textile production process.
Various Classes and Types of Dyes
Acid Dyes
A class of dyes used on wool, other animal fibers, and some manufactured fibers. Acid dyes are seldom used on cotton or linen since this process requires a mordant. Acid dyes are widely used on nylon when high wash fastness is required. In some cases, even higher wash fastness can be obtained by after treatment with fixatives.
Natural Dyes
Direct Printing, it is the most common approach to apply a color pattern onto a fabric. If done on colored fabric, it is known as overprinting. The desired pattern is produced by pressing dye on the fabric in a paste form. To prepare the print paste, a thickening agent is added to a limited amount of water and dye is dissolved in it. Earlier starch was preferred as a thickening agent for printing. Nowadays gums or alginates derived from seaweed are preferred as they allow better penetration of color and are easier to wash out. Most pigment printing is done without thickeners because the mixing up of resins, solvents and water produces thickening anyway.
Direct (Substantive) Dyes
Direct dyes color cellulose fibers directly without the use of mordants. They are used for dyeing wool, silk, nylon, cotton, rayon etc. These dyes are not very bright and have poor fastness to washing although they are fairly fast to light.
Basic (Cationic) Dyes
Basic dyes are water-soluble and are mainly used to dye acrylic fibers. They are mostly used with a mordant. A mordant is a chemical agent which is used to set dyes on fabrics by forming an insoluble compound with the dye. With mordant, basic dyes are used for cotton, linen, acetate, nylon, polyesters, acrylics and modacrylics. Other than acrylic, basic dyes are not very suitable for any other fiber as they are not fast to light, washing or perspiration. Thus, they are generally used for giving an after treatment to the fabrics that have already been dyed with acid dyes.
Synthetic Dyes
Synthetic dyes are classified based upon their chemical composition and the method of their application in the dyeing process.
Disperse Dyes
Disperse dyes are water insoluble. These dyes are finely ground and are available as a paste or a powder that gets dispersed in water. These particles dissolve in the fibers and impart color to them. These dyes were originally developed for the dyeing of cellulose acetate but now they are used to dye nylon, cellulose triacetate, and acrylic fibers too.
Sulfur Dyes
Sulfur Dyes are insoluble and made soluble by the help of caustic soda and sodium sulfide. Dyeing is done at high temperature with large quantities of salt so that the color penetrates into the fiber. After dyeing the fabric is oxidized for getting desired shades by exposure to air or by using chemicals. Excess dyes and chemicals are removed by thorough washing. These dyes are fast to light, washing and perspiration and are mostly used for cotton and linen.
Pigment Dyes
Although pigments are not dyes in a true sense, they are extensively used for coloring fabrics like cotton, wool and other manmade fibers due to their excellent light fastness. They do not have any affinity to the fibers and are affixed to the fabric with the help of resins. After dyeing, the fabrics are subjected to high temperatures.
Mordant Dyes
The mordant or chrome dyes are acidic in character. Sodium or potassium bichromate is used with them in the dye bath or after the process of dyeing is completed. This is done for getting the binding action of the chrome. They are mostly used for wool which gets a good color fastness after treatment with mordant dyes. They are also used for cotton, linen, silk, rayon and nylon but are less effective for them.
Vat Dyes
Vat dyes are insoluble in water and cannot dye fibers directly. However, they can be made soluble by reduction in alkaline solution which allows them to affix to the textile fibers. Subsequent oxidation or exposure to air restore the dye to its insoluble form. Indigo is the original vat dye. These dyes are the fastest dyes for cotton, linen and rayon. They are used with mordants to dye other fabrics such as wool, nylon, polyesters, acrylics and modacrylics.
Reactive Dyes
Reactive dyes react with fiber molecules to form a chemical compound. These dyes, they are either applied from alkaline solution or from neutral solutions which are then alkalized in a separate process. Sometimes heat treatment is also used for developing different shades. After dyeing, the fabric is washed well with soap so as to remove any unfixed dye. Reactive dyes were originally used for cellulose fibers only but now their various types are used for wool, silk, nylon, acrylics and their blends as well.
Naphthol Dyes
A type of azo compound formed on the fiber by first treating the fiber with a phenolic compound. The fiber is then immersed in a second solution containing a diazonuim salt that reacts with the phenilic compound to produce a colored azo compound. Since the phenolic compound is dissolved in caustic solution, these dyes are mainly used for cellulose fiber, although other fibers can be dyed by modifying the process. (Also see DYES, Developed Dyes.)
Digital Textile Printing
Directly printing colors and patterns onto fabric using design software, large-format printers, and specialty inks made with pigments or dyes. Digital printing is an alternative to standard screen printing, which uses a constrained color palette and requires separate stencils and production steps for each color.
Bleeding and Crocking
Two components of colorfastness. Bleeding happens when dye comes off a fabric in contact with liquid. Crocking occurs when a dye on a dry fabric rubs off on another dry fabric.
Colorfastness
The ability of a dye to preserve the original color during industrial processing and subsequent customer use. The American Association of Textile Chemists & Colorists provides several dozen test methods to ensure colorfastness of dye products.
Application of Dyes
| Name of Dyes | Application |
|---|---|
| Acid Dye | Man made fiber (Nylon), Natural Fiber (Silk, Wool) |
| Direct Dye | Man made fiber (Viscose), Natural Fiber (Cotton) |
| Vat Dye | Man made Fiber (Viscose), Natural Fiber (Cotton, Silk, Wool) |
| Disperse Dye | Nylon, Polyester, Acrylic, Tri-acetate, Di-acetate |
| Basic Dye | Jute, Acrylic |
| Reactive Dye | Cotton, Hosiery, Viscose |
| Sulfur Dye | Cotton, Viscose |
| Mordant Dye | Cotton, Wool, Silk |
| Pigment | Cotton, Man made Fiber |
| Mineral | Cotton, Wool, Silk |
| Azoic Dye | Cotton, Viscose |
| Aniline | Black Cotton |
| Rapid and Rapidson Dye | Cotton |
| Onium Dye | Cotton, Jute |
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