Fabrics made of a polyester cotton blend are exactly what they sound like, made from fibers of both the natural cotton and the synthetic polyester. While both fibers have pros and cons, a blend is often used in garments to give the consumer the benefits of both.

POLYESTER

Polyester is a manmade polymer material. It is made from coal, air, water and petroleum products. Polyester is a strong fiber that keeps its shape and therefore resists wrinkling. The fiber does not withstand medium to high temperatures and melts and burns at the same time, therefore ironing polyester must be done at a cool temperature, if at all. Threads of polyester last for a long time and wear well, so are used for many garments and sewing projects. Polyester does not shrink like its natural counterpart and holds dye extremely well, a good thing for textile artists, but bad for stain-removal from polyester items. Polyester was extremely popular in the 1950s but since then is used more as a blend than the main fiber used for garments or fabric.

COTTON

Cotton is an all-natural fiber made from the pod of a cotton plant. It is the principal fiber used in making the world's clothing. Cotton is known for being light, cool, comfortable and absorbent. Many people describe cotton as a fabric that "breathes." It is also easy to dye and to clean, though dyes do not hold as fast to natural fibers as to the synthetic fibers of polyester. Cotton can withstand high temperatures, but does wrinkle easily and shrinks with washing.

BLEND BENEFITS

A polyester cotton blend can be versatile, as it most likely retains the coolness and lightness of the cotton fiber, but also adds the strength, durability and wrinkle-resistance of polyester. A polyester cotton blend should only shrink slightly in comparison to a garment or fabric that is 100 percent cotton. This blend is often preferred by at-home sewers and quilters as it is extremely easy to sew.

BLEND CONS

Adding polyester to cotton can cause unattractive pilling of the fabric and make the fabric not withstand high temperatures as well. Many people prefer pure cotton to a polyester blend

cotton in clothing that they need to breathe, as the blend does not breathe or stay as cool as pure cotton.

USES

Polyester cotton blend is mostly used in the garment industry to make clothing that people want to be able to wash and wear without having to iron and that will be tougher than a 100 percent cotton blend and withstand more washing. Many home sewers prefer polyester cotton blends as it is more forgiving and easy to sew than pure cotton, as it wrinkles and shrinks less.

WET PROCESSING

PRETREATMENTS: Thorough pretreatment of the cotton component of polyester cotton (P/C) fabric is essential for proper dyeing, printing or finishing as it improves absorption of dye liquor and other chemicals by water.

The following two sequences of pretreatment processes are usually carried out on commercial scale processing of polyester cotton fabrics.

SEQUENCE I: 1. Singeing

2. Desizing

3. Scouring

4. Bleaching

5. Mercerizing or Causticizing

6. Drying

7. Heat setting

For p/c fabric above sequence is more commonly used because it is cheaper (one drying only)

SEQUENCE II: 1. Desizing

2. Drying

3. Heat setting

4. Singeing

5. Scouring

6. Bleaching

7. Mercerizing or Causticizing

8. Drying

This sequence gives better results as after the removal of sizing material the fibers become in raised form on the surface of the fabric and are completely removed during the process of singeing.

DYEING OF POLYESTER COTTON BY EXHAUST PROCESS Dyeing can be carried out by using disperse-direct , disperse-reactive, disperse-Vat and disperse-sulphur dyes by following methods

ONE BATH ONE STAGE EXHAUST PROCESS In this process both fibers are dyed simultaneously in the same liquor, this method is suitable for:

Disperse-Direct Dyes

ONE BATH TWO STAGE EXHAUST PROCESS In this process both fibers are dyed in the same liquor but in two stages either polyester or cotton is dyed at first and then the remaining component is dyed in the same liquor, this method is suitable for:

Disperse-Direct Dyes

Disperse-Reactive Dyes

Disperse-Vat Dyes

Disperse-Sulphur Dyes

TWO BATH TWO STAGE EXHAUST PROCESS In this process both fibers are dyed separately in seprate liquor in two stages either polyester or cotton is dyed at first and then the remaining component is dyed, this method is suitable for:

Disperse-Direct Dyes

Disperse-Reactive Dyes

Disperse-Vat Dyes

Disperse-Sulphur Dyes

DYEING OF POLYESTER COTTON BY CONTINUOUS PROCESS Continuous dyeing of p/c fabric generally carried out by:

Disperse-Vat Dyes or Disperse-Sulphur Dyes

Continuous dyeing of p/c fabric is also carried out by PIGMENTS