GATE (TF) Textile 2011 Question Paper Solution | GATE/2011/TF/40

Sodium formaldehyde sulfoxylate (SFS) is a reducing agent that is used in the textile industry for various purposes. One of its main uses is as a bleaching agent for fabrics and fibers.
When used as a bleaching agent, SFS is typically combined with hydrogen peroxide and an alkali to form a bleach bath. The SFS reduces the colorants in the fabric or fiber, making them more soluble and easier to remove. This process is commonly used to remove unwanted color from textiles, such as stains or natural colorants, or to achieve a lighter shade for dyeing.
SFS can also be used as a reducing agent in textile printing, where it is used to remove excess dyes or pigments from the fabric to create a more even and consistent color. It can also be used as a dye stripper to remove unwanted dyes from textiles.
In addition to its use as a bleaching and reducing agent, SFS can also be used as a stabilizer for vat dyes, which are commonly used in the textile industry. It helps to maintain the solubility of the dye and prevent it from precipitating out of the dye bath.
However, it is important to note that SFS is a hazardous chemical and should be handled with care. It can release harmful fumes and should only be used in well-ventilated areas with appropriate protective equipment.

Urea is a nitrogen-containing compound that is widely used in the textile industry for various purposes. Some of its main uses include:
Textile dyeing and printing: Urea is used as a dyeing auxiliary to improve the dye uptake of fibers, especially for cellulosic fibers like cotton, rayon, and linen. It helps to increase the solubility of dyes and prevent dye precipitation, resulting in more even and vibrant colors. Urea is also used as a printing auxiliary to improve the color yield and sharpness of the printed designs.
Textile finishing: Urea is used as a finishing agent to impart softness, smoothness, and wrinkle resistance to fabrics. It can be applied by padding or spraying the fabric with a urea solution, followed by curing or drying to fix the finish. Urea finishes are often used on cotton, wool, and silk fabrics to improve their hand and appearance.
Textile washing: Urea is used as a washing auxiliary to enhance the cleaning performance of detergents and reduce the water hardness. It acts as a complexing agent for metal ions in the water, preventing them from interfering with the detergent action and reducing the formation of insoluble residues on the fabric.
Textile fiber production: Urea is used as a spinning solvent for synthetic fibers, such as nylon and polyester, to improve their spinning properties and reduce the viscosity of the spinning solution. It can also be used as a component of sizing agents to improve the adhesion of fibers and reduce yarn breakage during weaving or knitting.
Overall, urea is a versatile chemical that plays an important role in various aspects of textile processing, from fiber production to finishing and care.

Resist salt, also known as sodium alginate, is a common thickener used in textile printing to create sharp and well-defined patterns. It is derived from seaweed and is a natural, biodegradable, and non-toxic alternative to synthetic thickeners.
When mixed with water, resist salt forms a viscous solution that can be applied to the fabric using a printing screen or roller. The resist salt solution is applied to the fabric in the areas where the print design is not desired, forming a barrier that prevents the dye from penetrating the fabric fibers. The dye is then applied to the exposed areas of the fabric, where it bonds with the fibers to create the desired color.
Resist salt is especially effective for printing on natural fibers like cotton, silk, and wool, which have a tendency to absorb dye unevenly and bleed into neighboring areas. By forming a resist barrier, resist salt helps to control the spread of the dye and create sharp, well-defined patterns.
Resist salt can also be combined with other thickeners and additives to achieve specific printing effects, such as metallic or glittery finishes, embossed textures, or raised prints. It is compatible with a wide range of dyes and pigments, and can be used for both direct and discharge printing techniques.
Overall, resist salt is a versatile and essential component of textile printing, providing a safe and eco-friendly way to achieve high-quality and long-lasting prints.

Carboxymethyl cellulose (CMC) is a water-soluble polymer derived from cellulose, a natural polymer found in plant cell walls. CMC is widely used in the textile industry as a thickener, binder, and sizing agent. Some of its main uses include:
Textile printing: CMC is used as a thickener and binder in textile printing pastes to improve their viscosity, stability, and adhesion. It helps to prevent the dyes and pigments from bleeding or spreading on the fabric, resulting in sharp and well-defined prints.
Textile finishing: CMC is used as a sizing agent to improve the strength, smoothness, and wrinkle resistance of fabrics. It can be applied by padding or spraying the fabric with a CMC solution, followed by drying or curing to fix the sizing. CMC sizings are commonly used on cotton, rayon, and synthetic fabrics to improve their weaving or knitting properties.
Textile dyeing: CMC is used as a dyeing auxiliary to improve the dye uptake and uniformity of fibers, especially for cellulosic fibers like cotton, linen, and rayon. It helps to increase the solubility of dyes and prevent their precipitation, resulting in more even and vibrant colors.
Textile care: CMC is used as a soil release agent in laundry detergents to help remove dirt and stains from fabrics. It acts as a protective film that prevents the dirt from adhering to the fabric fibers and facilitates their removal during washing.

Overall, CMC is a versatile and widely used chemical in the textile industry, providing various benefits in textile processing, finishing, and care. It is a safe and eco-friendly alternative to synthetic thickeners and sizing agents, and can be easily modified to achieve specific properties and functions.