Dyeing Fabrics

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  • Topic: Dye, Dyes, Nylon
  • Pages : 12 (3674 words )
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  • Published : February 28, 2013
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PICRIC ACID (DIRECT DYE):
Take about 60 mL of water in a 400 mL beaker. Add 2-3 drops of concentrated sulphuric acid and about 0.5 g of Picric Acid to it. Stir the solution with a wooden stick and warm over a hot water bath. Immerse one piece of each wool, cotton, polyester, nylon and terecot into it. When the pieces are thoroughly wetted in dye solution remove these with the help of forceps. Wash these with the help of warm water till the washing is colourless. Dry the pieces and note the results.

INDIGO (VAT DYE):
Take about 50 mL of water in a beaker. Add about 0.1 g (one pellet) of sodium hydroxide, 0.1 g of Indigo and 0.5 g of sodium hydrogen sulphite and shake gently until the solution becomes somewhat green. (Add some more sodium hydrogen sulphite if the Indigo powder did not dissolve). Immerse the pieces of cotton, polyester, nylon, terecot and wool in the dye solution. When the pieces are thoroughly wetted in dye solution remove these with the help of forceps and squeeze between folds of rough filter paper. Hang the pieces to dry in air and allow the leuco Indigo to become oxidized to blue indigo. Wash the pieces well with water and note the results.

PHENOLPHTHALEIN:
Take about 50 mL phenolphthalein in a beaker. Immerse the pieces of cotton, polyester, nylon and wool in the dye solution. When the pieces are thoroughly wetted in dye solution remove these with the help of forceps and allow them to dry in air and note the results.

PHENOLPHTHALEIN (IN SODIUM HYDROXIDE):
Take about 50 mL phenolphthalein in a beaker. Add a few drops of sodium hydroxide to it. Immerse the pieces of cotton, polyester, nylon and wool in the dye solution. When the pieces are thoroughly wetted in dye solution remove these with the help of forceps and allow them to dry in air and note the results.

METHYLENE BLUE:
Take about 50 mL of methylene blue in a beaker. Immerse the pieces of cotton, polyester, nylon and wool in the dye solution. When the pieces are thoroughly wetted in dye solution remove these with the help of forceps and allow them to dry in air and note the results.

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OBSERVATIONS

DYE

NATURE OF FABRIC

WOOL

COTTON
POLYESTER
TERECOT
NYLON

PICRIC ACID

INDIGO

PHENOLPHTHALEIN
PHENOLPHTHALEIN
(IN NaOH)

METHYLENE BLUE

RESULTS AND CONCLUSIONS

PICRIC ACID:
It is capable of dyeing all the fibres used effectively.

INDIGO:
It is able to dye all the fibres used with the exception of polyester cloth.

PHENOLPHTHALEIN:
It is unable to dye the fibres.

PHENOLPHTHALEIN (IN SODIUM HYDROXIDE):
It is able to dye only cotton and terecot fibres.

METHYLENE BLUE:
It is capable of dyeing all the fibres.

PRECAUTIONS

(I) Do not immerse your hands in the dye bath.
(II) Handle the materials carefully as most of these are toxic in nature.

INTRODUCTION

Dyeing is the process of coloring materials, such as textile fibers, so that the coloring matter becomes an integral part of the fiber. Dyes, or dyestuffs, are soluble compounds that can be either absorbed and retained by the fiber or chemically combined with it. Dyes are generally fast—that is, they retain their color in the fiber throughout the textile-making process and under exposure to normal wear, including sunlight, water, and detergent washing. Pigments are insoluble coloring compounds.

HISTORY

Dyeing was practiced in Egypt, Persia, China, and India thousands of years ago. Before 1856, natural materials derived from insects, plants, shellfish, and minerals were the only known sources of dyestuffs. These sources included the root of the herb madder for red dye and the indigo plant for blue dye. In the early days of the Roman Empire, garments colored with Tyrian purple, a dye derived from a shellfish of the Mediterranean Sea, were worn by the imperial family and the...
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