Different Stages of Dyeing Textiles
Textiles may be dyed at any stage of their development from fibre into fabric or certain garments by the following methods;
� Stock Dyeing : Stock dyeing refers to dyeing staple fibres before they are spun. Here the packed fibres are removed from the bales and then packed in large vats to be circulated with dye liquor at elevated temperature.
In stock dyeing, which is the most effective and expensive method of dyeing, the colour is well penetrated into the fibres and does not crack readily. Stock dyed fibres does not spin as readily as undyed fibre because it loses some of its flexibility, but lubricants added in the final stage overcome most of this difficulty.
� Top dyeing : Top dyeing is adopted in the worsted industry. Top is wool that has been combed to take out the short fabrics, in a rope like form about 1� inches (30mm thick). The top is then wound on perforated spools and the dye liquor is circulated through it. Perfect even dyeing is possible in this method.
Yarn Dyeing : Dyeing done at yarn stage is known as yarn dyeing. Yarn dyed fabrics are usually deeper and richer in colour. The primary reason for dyeing in the yarn form is to create interesting checks, stripes and plaids with different coloured yarns in the weaving process. Chambrays, for example, are usually woven with a coloured warp and white filling. Other examples are checked gingham, shepherds check, plaid and seer sucker.
Piece Dyeing : Bulk of fabrics are dyed in this method. Piece dyeing is thoroughly satisfactory as regards evenness, penetration and overall fastness.
Fabrics may be piece dyed whether it is composed of only one kind of fibre or yarn or blends of different fibres or combinations of different yarns. When the fabric is made of one kind of fibre or yarn, the dyeing is not complicated because the one appropriate dye is used. If the fabric is of a blend or combination of different yarns, then special procedures are required where different dyes that are particular for each fibre need to be selected. They are union dyeing and cross dyeing.
Union Dyeing: Different fibres may require different dyes to obtain the colour, this may be done by putting the appropriate colour dye that is specific to each type of fibre into one bath.
Cross Dyeing: Cross dyeing of goods may be accomplished in any one of the several ways. One method is a combination of stock dyeing or of yarn dyeing with subsequent fabric dyeing.
Solution pigmenting or Dope dyeing : A process called solution pigmenting or dope dyeing has been used for manmade fabrics ranging from rayon through saran and glass fibres. In dope dyeing, dye is added to the spinning solution before it is extruded through the spinnerets into filaments. This method also gives a greater degree of colourfastness. Effective results have been obtained by this method.
Garment Dyeing : Certain kinds of non-tailored apparel, such as hosiery, pantyhose and sweaters can be dyed as completed garments. A number of garments are loosely packed into a large nylon net bag. The bags are then put into a puddle dyer, which is a tub with a motor-driven puddle that agitates the dye bath. Garment dyeing is an economical method.
Resist Dyeing : Resist dyeing can be done either in garments or fabrics.
Resist dyeing is a term for a number of traditional methods of dyeing textiles with patterns. Methods are used to 'resist' or prevent the dye from reaching all the cloth, thereby creating a pattern and ground. The most common forms use wax, some type of paste, or a mechanical resist that manipulates the cloth such as tying or stitching. Another form of resist involves using a chemical agent in a specific type of dye that will repel another type of dye printed over the top. The most well-known varieties today include tie-dye and batik.
�Tie and Dye : Tie-dye is a process of resist dyeing textiles or clothing which is made from knit or woven fabric, usually cotton, typically using bright colors. Tie and dye developed especially in the regions of Gujarat and Rajasthan. People of Jaipur are particularly skilled in this craft. Tie-dyeing is accomplished by folding the material into a pattern, and binding it with string or rubber bands. Many different kinds of dyes can be used, mostly reactive dyes are used.
Tie dye is a technique for dying fabrics that results in interesting, colorful patterns. The technique involves crumpling, pleating or folding the fabric into various patterns, then tying it with string, hence the name 'tie and dye'. The tied fabric is dipped into vats of dye, then wrung out and rinsed. The ties prevent the entire material from being dyed. Designs are formed by applying different colors of dyes to different sections of the wet fabric. Tied areas accept dye unevenly amidst the folds, creating varied patterns in the finished product.
There are different types of methods of tying threads to obtain different patterns such as: Striped design - diagonal, vertical and horizontal stripes, Knotting, Circular design, Marbling, Rouching, All over tiny dots, Mango design and Flower design.
Batik : This is another form of resist dyeing which produces patterns like prints. The difference between 'tie and dye' and 'batik' lies in the fact that former is by tying the spots and latter applying wax on the cloth. The word 'batik' origin is Javanese, meaning 'to tattoo'. The fabric used for batik should be smooth and thin in order to get a good effect. Silk is perhaps the easiest fabric of all to use. Other fabrics suitable for this are soft cotton and organdie. Any fabric for making batik should be thoroughly washed and ironed before use.
Design is traced lightly to the fabric with sharp pencil. Brushes of various sizes will be needed to apply hot liquid wax on the design. Bees wax is the best wax to use for batik. Then the fabric is dyed. The wax prevents the dye to from penetrating into the design. The finished fabric is left with a white pattern on a coloured background. The wax is sometimes deliberately cracked to form a fine spider-like line of colour where the dye penetrates these cracks.