Shrinkage & Skewing
What is Shrinkage?
Learn more about the basics of shrinkage:
Impact of Shrinkage
Shrinkage of textile and apparel products has always had a profound effect on design and production planning in all areas of textile and apparel manufacturing. In today’s competitive markets, where high quality is expected at a low price, apparel companies are demanding products with low levels of shrinkage from their suppliers.
Shrinkage Defined
“Dimensional change” means any change in dimensions of a fabric or garment, whether positive or negative. A positive change in dimensions is “growth,” and a negative change in dimensions is “shrinkage.” In garments, shrinkage characteristics relate not only to dimensional changes, but also to changes such as seam puckering and skew, changed relationships between the body cloth and trim components, and changes in fit. For the purposes of this course, shrinkage is defined as “a dimensional change in a fabric or garment caused by an application of a force, energy, or a change in the environment that either allows the goods to relax or forces the fabric to move in a given direction.”
Types of Shrinkage
Shrinkage and its causes can be broken down into two types: construction shrinkage and processing shrinkage. This means that shrinkage is affected both by the fabric’s construction parameters and by the forces applied during dyeing and finishing. Sewing and finishing processes during apparel manufacturing also can affect shrinkage. The shrinkage of a product is affected by both application and removal of stresses.
Physics of Shrinkage
Science tells us that the lowest energy state for a flexible rod is that of a straight rod. From a physics perspective, yarn is a flexible rod. The yarn is bent to form the loops in knits and the warp and filling yarns in weaving. The bending of the yarn and the amount of open space in the fabric determine the amount of shrinkage resulting from removal of stress on the yarns and reduction in the openness of the fabric.
One of the most important aspects of an apparel item or home product is its dimensional stability to laundering. There may be no worse attribute than a shirt, slack, or sheet that shrinks or grows and no longer fits properly. Controlling shrinkage of textile and apparel products impacts the design and production planning in manufacturing or sourcing products and must be addressed in the supply chain.
Understanding & Overcoming Shrinkage
Learn how you can overcome shrinkage issues within the supply chain and grow your cotton business.
Don Bailey, Textile Technology Instructor, covers design, construction, dyeing, and finishing parameters that affect or improve shrinkage and what you need to know when sourcing cotton products. This webinar covers the impact of fabric density (cover factor), fabric type, wet processing techniques, chemistry, physical finishing, and compaction. It also takes a closer look at the impact of heat on cotton relaxation and the effects on productions costs were discussed.
One of the most important aspects of an apparel item or home product is its dimensional stability to laundering. There may be no worse an attribute than a shirt, slack, or sheet that shrinks or grows and no longer fits properly. Controlling shrinkage of textile and apparel products impacts the design and production planning in manufacturing or sourcing products and must be addressed in the supply chain.
Technical Bulletin: “Guide to Improved Shrinkage Performance of Cotton Fabrics”
To be competitive, apparel companies need to ensure that shrinkage is low and is consistent from garment to garment. However, rigid and arbitrary fabric shrinkage specifications are not the answer. Instead, apparel firms and mills need to work as partners, to ensure that cotton apparel products are planned and engineered in such a way as to control shrinkage while meeting other requirements and expectations.
In this bulletin, we explore in detail the types and causes of shrinkage in cotton fabrics and describe methods for reducing shrinkage. The key to success is to engineer the product from fiber selection through all processing steps, setting reasonable specifications based on construction parameters and taking into account how shrinkage is affected by fiber, yarn size and type, construction variables, wet-processing procedures, finishing procedures, apparel manufacturing processes, and garment care labeling and laundering practices.
Technical Bulletin: “Wet Processing of 100% Cotton Knitted Fabric”
It is well established that knitted fabrics of all constructions and fiber blends are inherently more prone to shrinkage as compared to wovens. Because of the inability of a knitter to form a knitted fabric with no shrinkage, it is important for the dyer and finisher to make an effort to remove as much shrinkage from the product as possible. However, the ease with which a cotton knitted fabric is distorted during processing makes it especially difficult to deliver fabrics with no shrinkage. This bulletin will discuss in some detail the aspects of knitted fabric construction and wet processing and how they are related in terms of shrinkage.
The factors that influence the level of dimensional stability can be summarized as follows:
- Knitting parameters
- Processing tensions after knitting
- Relaxation techniques in finishing
- Mechanical and chemical finishes
Each of these areas can be broken down into fundamental aspects.
Knit Fabric Shrinkage
The most important factors relating to shrinkage are fiber, yarn, construction, wet processing, finishing procedures, cut-and-sew techniques, and garment care. Construction and processing shrinkage depend on the construction and processing variables chosen by the manufacturer or customer. Knit fabrics typically are more open and loose in structure than wovens and thus are subject to more instability and dimensional change. To understand shrinkage in knit fabrics, it is important to fully understand the basics of loop formation, the consolidation forces in dyeing and finishing, and the effects of product care.
Knitting Parameters
Learn about knit fabric construction parameters that relate to shrinkage are fiber type, yarn type and structure, type of knitting stitch, stitch length, and finishing techniques. The product specifications serve as the blueprint for the selection of these parameters. These in turn influence the potential for dimensional change in the product.
Dyeing & Finishing Parameters
Wet processing procedures usually create stress on a fabric. Continuous processes during preparation and dyeing and preparation for drying usually stretch the length or reduce the width. If these forces are great, they may exceed the elastic limit, thus permanently changing the fabric’s relaxed dimensions. Finishing procedures may reduce or improve the fabric’s dimensional stability. The use of relaxation dryers, compactors, or crosslinking agents can reduce the residual shrinkage after wet processing. Without these measures, there will be little or no reduction of shrinkage.
Chemical Finishing
For years, chemical crosslinking has been commonly used to stabilize cotton and other natural-fiber knit fabrics, especially in open-width form. Compaction methods, although effective, are used primarily on knits such as underwear fabrics and tubular goods. Improvements in wet processing methods resulting in lower tensions on fabric, such as the evolution of relaxation dryers and the improvement of compaction machinery, have reduced the need for chemical finishing. However, many cotton products continue to use crosslinking agents because of the desire for low shrinkage without the increased bulk resulting from compaction.
Measuring the Shrinkage of Fabrics & Garments
Many methods exist for measuring the shrinkage of cotton fabrics and garments. The most reliable methods use a system that properly prepares the sample for the test, agitates the goods without tensions or restrictions on the fabric, and measures the results accurately.
Fabric Defects: Skewing
Skew problems in your product line? Let’s take care of that.
Watch Understanding & Overcoming Skewing. Learn to improve the performance of your quality goods as textile expert Don Bailey delves into key textile techniques. This insightful webinar is part of our ongoing Sourcing the Best Cotton Products series.
- Download Understanding & Overcoming Skewing slides.
- Download Understanding & Overcoming Skewing Q&A.
