Types of Dyes

Types of Dyes                

For dyeing any type of fabric the type of dye should be properly selected keeping in mind the type of fabric. If you use cotton dye on polyester and polyester dye on cotton it won’t give good results.

About the Dyes

Dyes are classified into following types:-

Vat dyes  :- These dyes are used for dyeing materials like cotton. These dyes are water insoluble and therefore has to be converted to water soluble  compounds with the help of a reducing agent before dyeing the fabric. The fabric is then dyed in this water soluble dye and exposed to air or to a chemical oxidizing agent, and the dye reverts to its insoluble form. These dyes are extremely fast.

E.g. Indigo is a type of Vat Dye

 Acid dyes :- Acid dyes are water-soluble and can be applied directly to the fiber. They are used to dye protein fibres like silk, wool, angora, cashmere and mohair. Synthetic fibres like Nylon are also dyed with Acid dyes

Union Dyes:- these dyes are the combination of acid dyes with direct dyes. Acid dyes work on protein fibres like silk, wool and man made fibre like nylon while direct dyes work on cotton.

Fibre reactive dyes:- Reactive dyes are very fast as they become the part of the substrate molecule. Fiber reactive dyes can be used to dye wool by boiling with vinegar (acid). Reactive dyes will bind to protein fibers at any of a wide variety of pHs (acid/alkaline balance). Silk can also be dyed with fibre reactive dyes.

Azo Dyes.:- It is one of the most important Fibre reactive dye. The dyeing properties of Azo dyes are based on their linkage by a nitrogen, or azo bond.

Dispersed dyes:- Disperse dyes soluble in acetate but not water, are used to dye polyester, polyamides, acrylic and other synthetic fibers.

Basic dyes:- Basic dyes include most of the synthetic dyes. They are cationic (that is, they have a positive electrical charge) and are used for anionic (negative-charge-bearing) fabrics such as wool, silk, nylon, and acrylics.

Sulfur dyes:- They  are insoluble dyes, used to produce deep shades on cotton. They are  inexpensive and  made by  reaction of various organic chemicals with sulfur or sodium sulfide

Direct dyes

The colors of direct dyes are duller than those provided by fiber reactive dyes, and the washfastness is poor but are more light proof. Direct dyes are azoic dyes to which common salt or sodium sulfate has been added; they can be applied directly to cotton or other cellulosic fibers such as flax, jute, or paper, without pretreatment of the fiber with a mordant so they are called as direct dyes.

Metal-complex dyes, used primarily on wool, are combinations of a dyestuff and a metal, usually chrome. They are highly light-and wash-fast.

Natural Dyes

Nowadays mostly all of the natural dyes are replaced by synthetic dyes as synthetic dyes are much cheaper  and more fast. Natural dyes are classified into three categories plant dyes, animal dyes and mineral dyes.

Some natural dyes are:- Annotto, a natural dye derived from seeds of plant is orange red in color. Berberill and Turmeric are yellow in color. Brazil wood and lac are red in color.iron Buff is a buff color dye used to dye cotton.Kermes and Scarlet are derived from insects and used to dye cotton and linen. Log wood is used to dye  Silk ,wool and cotton.

Fabric Paints:-Fabric paints may be used on any type of fiber that can tolerate any required heat-setting. Fabric paint is a mixture of a pigment and a glue