Preparation of wool fabric for printing

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Preparation of wool fabric for printing:


Wool is a natural protein fiber. To make wool useful for dyeing and printing, its impurities must be removed. Wool usually contains mineral matter including Wool Wax or Grease, Dirt, and Burrs as waste.

Wool is usually cleaned in two steps. E.g.

1. by wool scouring.

2. by carbonization.

1. Preparation of wool fabric for printing by wool scouring:

In this method oil, fat, wax, dust, and sand are removed from the wool. Wool fibers are quickly damaged by Alkali. That is why strong alkaline sodium hydroxide (NaOH) can never be used in scouring. So mild alkaline sodium carbonate (Na2CO3) and ammonia carbonate for wool can be used. Wool can be scoured in different machines in the form of raw wool fiber, in the shape of yarn, and as a fabric. After scouring, the wool is washed and taken to the drying machine for drying.

2. Preparation of wool fabric for printing by carbonization:

This method removes naturally occurring vegetable matter from wool such as dry grass, hay, and other plant matter (cellulose fiber). In this method, after soaking the wool in sulfuric acid (H2SO4) solution for 2-3 hours, the excess acid liqueur is removed by the hydro extractor and after drying in the drying chamber, baking is done in the baking chamber at a temperature of 99°C – 110°C for 5 minutes. Then the plant cellulose is converted into hydro cellulose. The hydro cellulose is crushed with a roller and turned into a powder. The wool is then washed and quenched with sodium carbonate. In this way, natural vegetable matter can be removed from wool.

Chemical For Wool Fabric

Naturally, wool fibers are of the yellow type. This is the natural color of wool. Wool needs bleaching to remove the natural yellow color. Wool cannot be bleached with any hypochlorite and bleaching powder. This is because the oxidizing bleaching agent contains chlorine, which reacts directly with the protein fibers and damages the fiber.

This is why wool is bleached with reducing agents such as sulfur dioxide (SO2). Wool can also be bleached with the bleaching agent hydrogen peroxide. Sometimes sulfur dioxide and hydrogen peroxide both act as bleaching agents.

Preparation of wool fabric for printing:

Although it is satisfactory for wool dyeing, affinities are less seen to be addicted to its printing color. In this case, chlorination is done to increase the printing capacity of the fabric. This cold chlorine solution is usually made by mixing 1 gallon of 8 Tw in every 100 gallons of water containing sodium hypochlorite or chloride of lime.

Sulfuric acid is added to the mixture by treating the cloth while it is being washed and it is washed with water till the traces of chlorine are removed from the cloth. Antichlor treatment is then done by sodium bisulfite. In this case, the wool cloth is suitable for printing. Wool can be dyed and printed in different conditions. Wool yarn can also be printed, which creates a multi-color effect on the fabric after weaving.

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