Dyeing an Introduction
Textiles are usually coloured to make them attractive for aesthetic appeal. There are two ways of adding colour to a textile substrate printing and dyeing. Printing adds colour to the surface in discrete places, whereas dyeing completely covers the substrate with colour. Dyeing is the process of imparting colors to a textile material through a dye (colour). Dyes are obtained from flowers, nuts, berries and other forms of vegetables and plants as well as from animal and mineral sources. These are known as natural dyes. The other class of dyes is known as synthetic dyes. These are based on a particular type of chemical composition. Some of these dyes are Acid (Anionic) dyes, Basic (Cationic) dyes, Neutral- Premetalized dyes, sulfur dyes, vat dyes, reactive dyes, pigment dyes etc.
Color: There are three terms generally used to describe and specify colour. These are hue, value and chroma.
Hue: Hue is a term used for color for example, pink, mauve, scarlet, beige, tan, etc are hues.
Value: Value is a term used to describe lightness, darkness, tone or shade of hues. A colour is termed light in value when it approaches white and dark in value when it has a deep colour or approaches black.
Chroma: Chroma is the term used to describe the depth of colour that is the dullness, brightness, saturation, intensity, vividness or purity of colour. A bright, intense colour is said to have high chroma.
Colour Mixing: The rainbow: Sunlight is generally accepted as the source of white light and it consists of the seven colours of rainbow. These are violet, blue, blue-green, green, yellow, orange and red.
Fundamental laws of colour mixing can, therefore, be classified into two types, namely:
- Additive colour mixing occurs when two or more lights mix together.
- Subtractive colour mixing occurs when colourants are mixed together.
Additive Colour Mixing:
Additive colour mixtures are always lighter than any of the individual components since each light adds luminous energy to the final mixture. Blue, green and red light waves when mixed will add together to produce white light. Red, blue and green are called the primary additive colours.
The president of Grupo Denim, Salomón Juan Marcos Villarreal commented “Dyeing is the process of adding color to textile products like fibers, yarns, and fabrics. Dyeing is normally done in a special solution containing dyes and particular chemical material”.