What is knit fabric shrinkage? How to control
Knit fabric shrinkage refers to the amount of shrinkage that occurs when a knit fabric is washed or dried. Knit fabrics are made from interlocking loops of yarn, and they can be prone to shrinking because the fibers in the yarn can compress and interlock further when exposed to moisture and heat.
The amount of shrinkage that occurs in knit fabrics can vary depending on a number of factors, such as the type of fiber the fabric is made from, the construction of the fabric, and the care instructions provided by the manufacturer. Some knit fabrics may shrink only a little bit when washed, while others may shrink significantly.
It is important to take into account the potential for shrinkage when working with knit fabrics, as it can affect the fit and overall appearance of a garment. To minimize shrinkage, it is recommended to follow the care instructions provided by the manufacturer, such as washing in cold water and laying flat to dry.
Causes of Fabric Shrinkage:
Fabric shrinkage can be caused by a number of factors, including:
Heat:
Exposure to heat, whether from washing, drying, or ironing, can cause the fibers in the fabric to compress and interlock, leading to shrinkage.
Moisture:
Wetting the fabric can cause the fibers to swell and interlock, which can result in shrinkage when the fabric dries.
Agitation:
Agitating the fabric, such as in a washing machine or dryer, can cause the fibers to rub against each other and interlock, leading to shrinkage.
Fiber type:
Some types of fibers are more prone to shrinkage than others. For example, natural fibers such as cotton and wool tend to shrink more than synthetic fibers like polyester.
Fabric construction:
The way the fabric is constructed can affect its shrinkage potential. Knit fabrics, for example, are more likely to shrink than woven fabrics.
Quality of the fabric:
Lower quality fabrics may be more prone to shrinkage, as they may not be treated or finished to minimize shrinkage.
How to control shrinkage in compacting machine
Controlling shrinkage in fabric during the compacting process is essential to achieve the desired finished fabric dimensions. Here are some tips to control shrinkage at the fabric stage in compacting machines:
Fabric selection:
Choosing the right fabric with the appropriate weave and weight can help minimize shrinkage during the compacting process.
Proper pre-treatment:
Adequate pre-treatment, such as washing and rinsing the fabric, can help eliminate any shrinkage that may occur during the compacting process.
Control temperature and humidity:
Temperature and humidity play a significant role in the compacting process. Maintaining consistent temperature and humidity levels in the compacting machine can help control shrinkage.
Control speed:
Controlling the speed of the fabric through the compacting machine can also help minimize shrinkage.
Regular maintenance:
Regular maintenance of the compacting machine can help ensure that it is functioning correctly and prevent any issues that may lead to excessive shrinkage.
Use of chemicals:
In some cases, the use of specific chemicals during the compacting process can help control shrinkage. It’s important to follow the manufacturer’s recommendations for the use of chemicals and their concentration levels.
Overall, the key to controlling shrinkage in fabric during the compacting process is to maintain consistency in all factors that can influence the process.
Two types of shrinkage occur during washing:
Length wise
Width wise
Lengthwise shrinkage refers to the amount of shrinking that occurs in the length of a material, such as fabric or yarn, when it is washed or exposed to heat. This can happen because the fibers in the material contract, causing it to become shorter.
Widthwise shrinkage refers to the amount of shrinking that occurs in the width of a material when it is washed or exposed to heat. This can happen because the fibers in the material pull closer together, causing it to become narrower.
Both lengthwise and widthwise shrinkage can vary depending on the type of material and how it is treated. It is important to consider these factors when choosing fabrics or other materials for a project, especially if shrinkage could affect the fit or appearance of the final product. To minimize shrinkage, it is often recommended to pre-wash fabrics before using them in a project.
Shrinkage is determined as;
Shrinkage % = {(length of fabric after wash) – (length of fabric before wash)} / (length of fabric before wash) x 100
Example,
Length of fabric before wash = 35 cm
Length of fabric after wash = 33 cm
Shrinkage % = {(33-35)/ 35} x 100
= -5.7%
Here, Shrinkage is -5.7%. Normally shrinkage is acceptable less than 5%.
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