Fabric Finishing Processes Quiz

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Questions and Answers

What is the primary goal of fabric preparation?

To enhance physical properties of fabric

To minimize the number of processing steps

To ensure fast color development

To achieve uniform absorption of water (correct)

Which of the following materials is considered a natural impurity in raw wool?

Chemical lubricants

Dyes

Synthetic fibers

Vegetable matter (correct)

Why is it important to remove impurities during fabric preparation?

To enhance water resistance

To reduce fabric weight

To prevent uneven dye application (correct)

To improve fabric durability

What term refers to the initial processes fabrics undergo before finishing and dyeing?

Textile wet processing (C) Signup and view all the answers

Which statement best describes the 'greige' state of a fabric?

A state without finishing treatments (C) Signup and view all the answers

What is a potential consequence of non-uniform water absorption in fabric?

Inconsistent dye reaction (B) Signup and view all the answers

How does consumer demand influence the processing steps of a fabric?

It determines color and finish requirements. (D) Signup and view all the answers

What is considered the 'overwhelming majority' of fabrics presented to consumers?

Bleached and dyed fabrics (A) Signup and view all the answers

What must be removed from raw cotton before dyeing to avoid complications?

Hydrophobic waxes (C) Signup and view all the answers

Which process is specifically used for preparing cotton fabrics before dyeing?

Mercerization (C) Signup and view all the answers

What is the main purpose of the desizing process?

To remove warp sizes (B) Signup and view all the answers

What is a common method used for desizing starch warp sizes?

Oxidation reaction (D) Signup and view all the answers

Which of the following fibers typically undergoes carbonization during preparation?

Wool (A) Signup and view all the answers

What is the effect of continuous processing compared to batch processing?

More fabric can be processed quickly (A) Signup and view all the answers

Which process helps improve the dye uptake of natural fibers like cotton?

Scouring (A) Signup and view all the answers

What is the primary purpose of scouring during fabric preparation?

To eliminate impurities (C) Signup and view all the answers

Which warp size is known for being recyclable and is often used in polyester yarns?

Polyvinyl alcohol (A) Signup and view all the answers

During the scouring process of cotton, what is typically the desired outcome?

Removal of natural oils (C) Signup and view all the answers

Batch processing of fabrics is primarily characterized by what feature?

Single vessel usage (B) Signup and view all the answers

What is the likely consequence of not removing warp sizes before dyeing?

Poor dye uptake (C) Signup and view all the answers

What factor is NOT considered when choosing a processing method for textile fabrics?

Color of fabric (A) Signup and view all the answers

What type of treatment is used on warp yarns to prevent excessive abrasion during weaving?

Warp sizing (C) Signup and view all the answers

What is the primary purpose of scouring cotton fabric?

To remove impurities and prepare for dyeing (B) Signup and view all the answers

Which agent is commonly used as a scouring solution for cotton?

Sodium hydroxide (B) Signup and view all the answers

What is the term used for the process of removing sericin from silk fabric?

Degumming (A) Signup and view all the answers

What temperature is typically recommended for scouring raw wool?

50 °C (B) Signup and view all the answers

Which of the following statements about bleaching wool fibers is true?

Special procedures are required to avoid damage when bleaching wool. (D) Signup and view all the answers

What is the benefit of mercerization applied to cotton?

Improved moisture absorbency (B) Signup and view all the answers

Which method is used for removing impurities from wool after it has been spun and woven?

Carbonization (A) Signup and view all the answers

What is the effect of applying strong acids in the carbonization process of wool?

It converts impurities to a brittle form (C) Signup and view all the answers

What is typically combined with sodium hydroxide during the mercerization process?

Sodium silicate (D) Signup and view all the answers

What type of chemistry is primarily used for bleaching cotton?

Oxidative chemistry (B) Signup and view all the answers

Why are synthetic fibers easier to scour than natural fibers?

Impurities are of known composition. (B) Signup and view all the answers

What is the typical temperature and duration for scouring synthetic fibers?

70 °C for 20-30 minutes (D) Signup and view all the answers

What kind of effect does mercerization have on cotton fibers' structure?

It swells the fibers, altering their internal structure. (C) Signup and view all the answers

Which chemical is often used as a stabilizer in the bleaching of cotton?

Sodium silicate (A) Signup and view all the answers

What is the purpose of heat setting in the preparation of thermoplastic synthetic fibers?

To provide dimensional stability and shape retention (D) Signup and view all the answers

During the drying phase of fabric preparation, what mechanism is used to straighten the fabric?

A weft straightener and tentering frame (C) Signup and view all the answers

Which organization provides specifications for evaluating fabric properties during preparation?

American Society for Testing and Materials (ASTM) (B) Signup and view all the answers

What is a significant environmental concern associated with the desizing process in fabric preparation?

Increased biological oxygen demand in effluent (A) Signup and view all the answers

What innovative scouring method has been developed to reduce environmental impact for cotton preparation?

Application of enzyme mixtures (C) Signup and view all the answers

Which treatment has been shown to enhance hydrogen peroxide bleaching of cotton efficiently?

Use of specific enzymes in combination with peroxide (B) Signup and view all the answers

What role do tenter frames play during the fabric drying process?

To maintain fabric dimensions under tension (A) Signup and view all the answers

What can be a consequence of not properly treating wastewater discharged from a textile plant?

Environmental contamination (A) Signup and view all the answers

Which of the following alternatives may reduce costs and environmental impact in fabric preparation?

Implementing enzyme mixtures for scouring (B) Signup and view all the answers

What is a potential drawback of using alternative chemistries in fabric preparation?

They are typically more expensive on a per-pound basis (A) Signup and view all the answers

What is the primary function of heat setting in fabric preparation?

To prevent further shrinkage and maintain shape (B) Signup and view all the answers

Which of the following chemical treatments can potentially damage both wool fibers and the environment?

Carbonizing wool with sulfuric acid (C) Signup and view all the answers

What innovative process has been explored for cotton scouring using plasma treatment?

Reducing harsh chemical usage (B) Signup and view all the answers

Study Notes

Fabric Finishing: Preparation Processes

Fabric finishing encompasses various processes like preparation, dyeing, printing, and chemical/physical finishing, tailored to end use, construction, and demand.
Fabrics rarely are sold in their raw "greige" state.
Preparation aims for uniform water absorption, impurity removal, and whiteness (if applicable), minimizing fabric damage.

Textile Wet Processing

Textile wet processing, crucial to preparation, uses water extensively.
Methods include batch processing (one vessel) and continuous processing (multiple vessels).
Continuous is often preferred for large volumes due to speed and less fabric waste during initial setup.

Desizing

Desizing removes warp-sizing agents applied during weaving—usually starch, carboxymethyl cellulose (CMC), or polyvinyl alcohol (PVA).
Starch desizing often uses α-amylase enzymes to hydrolyze starch, followed by a hot water rinse.
CMC desizing typically uses a warm water rinse at neutral pH.
PVA can be removed with a hot water rinse; recycling is possible after ultrafiltration.

Scouring

Scouring removes inherent and processing impurities from fabrics.
Methods depend on fiber type and impurities.

Scouring Specifics:

Cotton: High-temperature alkali, wetting agent, detergent, and chelating agent treatment to remove impurities and enhance absorbency.
Wool: Mild alkali and nonionic detergent at lower temperatures (around 50°C). Enzyme and solvent systems are also used.
Silk: Sericin (glue-like substance) is removed with mild alkali, detergents, and enzymes.
Synthetics: Scouring usually involves detergent and sodium carbonate at around 70°C for 20–30 minutes.

Bleaching

Bleaching removes natural color from fabrics. Mainly used on natural fibers.
Cotton: Typically uses oxidative chemistry (hydrogen peroxide). Alkaline conditions, a stabilizer, and lower temperature conditions are crucial to minimize damage. Also reductive bleaching is an alternative.
Wool and Silk: Hydrogen peroxide bleaching requires specialized procedures due to their sensitivity to alkali. Reductive bleaching, enzyme assistance, and combining oxidative/reductive methods are approaches.

Mercerization

Mercerization, a special process for cotton, treats with concentrated sodium hydroxide to improve luster, strength, absorbency, and dyeability. The alkali swells cotton fibers.

Carbonization

Carbonization converts cellulosic impurities in wool to a brittle form, allowing easier removal by mechanical means. A 5% sulfuric acid treatment, drying at around 55°C, heating to 100°C and crushing are steps.

Heat Setting

Heat setting stabilizes thermoplastic synthetic fibers (polyester, nylon) ensuring dimensional stability, shape retention, and crease resistance. The fabrics are heated under tension.

Drying

Multiple stages, such as using a weft straightener, a tentering frame, and a drying oven for final fabric straightening.

Quality Control

AATCC and ASTM methods evaluate fabric properties during preparation.
Modern textile plants have waste treatment facilities to meet discharge regulations.

Research and Future Trends

New enzyme-based scouring systems for cotton, plasma treatments for scouring, enhanced hydrogen peroxide bleaching, and alternative chemistries for carbonizing wool and other processes are underway. There's a push to lower environmental impact, however, these alternative chemistries aren't always cost-effective overall.

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Description

Test your knowledge on the various fabric finishing processes, including preparation, dyeing, printing, and desizing. This quiz covers essential methods in textile wet processing, focusing on the importance of uniformity and impurity removal in fabrics. Prepare to dive into the intricate details of fabric treatment!