Why do fabrics shrink? Shrinkage in Fabrics!
During the manufacturing process of fabric or we call it fabric processing, fabric comes in lot of tension and stretches when it moves from one machine to another which causes stretching in fabric structure and when this tension is removed, and fabric is relaxed it tends to get back in its original structure causing shrinkage.
Figure: Stretched Fabric (The structure in which the fabric is under tension) vs Relaxed Fabric (After wetting or by some industrial mechanical process the fabric is relaxed, so as the yarns comes closer to each other shrinkage of fabric occurs.)
Shrinkage is the reduction in the dimensions of a fabric or garment after washing, drying, or exposure to heat or moisture. It can be further defined as “a dimensional change in a fabric or garment caused by an application of a force, energy, or a change in environment that either allows goods to relax or forces the fabric to move in a given direction.” It can affect the quality, appearance, fit, and performance of fabrics and garments, and cause losses for manufacturers and retailers.
Types of shrinkage
Shrinkage can be classified into three main types:
Relaxation shrinkage occurs when the fibers or yarns relax and contract after being stretched or twisted during weaving, knitting, or finishing. Felting shrinkage occurs when wool fibers interlock and mat together under heat, moisture, and agitation, reducing the fabric area and thickness. Consolidation shrinkage occurs when synthetic fibers or blends shrink under high temperature or pressure, causing the fabric to become denser and stiffer.
Shrinkage can also be classified into two types according to the causes which results in shrinkage.
- Construction Shrinkage
- Processing Shrinkage
Construction shrinkage is defined as the amount of dimensional change in a fabric based solely on the construction variables used to create the fabric. It is measured after fabrication but before subsequent processes. Processing shrinkage is defined as the dimensional change that a process adds to or removes from the construction shrinkage of a fabric, and thereby changes the residual shrinkage accordingly. Length and width dimensions are both affected, and the fabrics may either be stretched or consolidated.
Factors affecting Shrinkage
Shrinkage is influenced by various factors, such as:
- Type, structure and composition of the fiber, yarn, and fabric
- The methods of weaving, knitting, dyeing, and finishing
- The washing and drying conditions
- The storage and handling of the fabric or garment
Some fibers, such as wool, cotton, and rayon, are more prone to shrinkage than others, such as polyester, nylon, and acrylic. Some fabrics, such as knits, wovens with low twist, and fabrics with high surface area, are more susceptible to shrinkage than others, such as wovens with high twist, fabrics with low surface area, and fabrics with dimensional stability finishes.
Effects of shrinkage
Shrinkage can reduce the quality, appearance, fit and performance of a textile product.
- Dimensional changes occur with products having poor shrinkage, such as length, width, and shape distortion.
- Aesthetic changes effects different properties of textile products such as color fading, pilling, wrinkling, and seam puckering.
- Functional properties such as reduced strength, elasticity, durability, and comfort are greatly affected.
- Shrinkage effects the economic aspect of textile products like increased production costs, customer dissatisfaction and returns.
- Fabric weight is also affected by shrinkage which is very important to determine quality and weight of fabrics. A higher shrinkage rate can result in a lower fabric weight per unit area, which can reduce the fabric quality and price.
Prevention of shrinkage
Following steps can be taken for controlling or minimizing shrinkage
- By using appropriate fiber, yarn, and fabric selection.
- Applying suitable weaving, knitting, dyeing, and finishing techniques.
- Following proper washing and drying instructions.
- Storing and handling the fabric or garment with care.
- Using pre-shrunk or shrink-resistant fibers or yarns.
- Applying relaxation, heat-setting, or anti-shrinkage finishes.
- Using gentle or cold wash cycles and low or no heat drying cycles.
- Avoiding excessive agitation or stretching.
- Using hangers or flat drying for garments.
Sanforizing Machine and Process
Sanforizing process moves the yarns closer together and the fabric becomes thicker and heavier. As a result of this, the net yardage yield is reduced. Sanforized is now used for a fabric which has low residual shrinkage and sanforization is a process for shrink-proofing fabrics.
Space Dyeing Techniques
"Space dyeing is a process of dyeing of yarn in which multiple colors are applied along the length of each strand of yarn which may or may not repeat after a fixed interval."
Worsted Yarn Manufacturing Process
A fine smooth yarn spun from combed long staple wool. Worsted yarns are more tightly twisted than the bulkier woolen yarns. The soft, heavy yarn is strong and durable and is often used for sweaters. Worsted yarns are also used for fine dress fabrics and suit materials.
Acrylonitrile Butadiene Styrene (ABS) Polymers History
Acrylonitrile-Butadiene-Styrene has been available since the 1940's. In attempts to produce bulletproof plastic sheets during the last years of World War II, polymer systems were developed from special butadiene acrylonitrile copolymers and styrene acrylonitrile copolymers with high molecular masses.