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What is Sizing in Fabric? Unraveling the Intricacies of Sizing

What occurs to your mind when it comes to the term “sizing”? Plus size? Petite size? However, it is more than a measurement of your daily wearing. In the textile industry,  sizing is a vital intermediate link impacting process implementation and product quality. 

This post will introduce and explain the complicated technical process with concise and readable words. You can harvest a lot within several minutes!

What is Sizing in Fabric?

Sizing

In the textile, sizing, also called warp sizing, is the process of applying a special substance to coat and infiltrate yarns. It is a requisite process between warp making and weaving.

Sizing Material

The technical term for the special substance applied is sizing material.  A sizing material involves one or more sizing agents in certain proportions. It adheres to and penetrates fabrics after being diluted by water. 

The recipe of sizing material contains the main adhesive and auxiliary,  for that a sole ingredient is unable to satisfy the demands of sizing. The adhesive determines the performance of sizing. It can be divided into 3 categories on account of the source and processing. Details and representatives are as follows.

  • Natural adhesive: plant starch, gelatin and so on.
  • Modified adhesive: modified starch, cellulose derivative and so on.
  • Synthetic adhesive: PVA (Polyvinyl Alcohol), PAAm (Polyacrylamide) and so on.

The auxiliary is implemented to perfect some qualities of the adhesive, such as permeability, antistatic property, and hygroscopicity.

History of Sizing

In ancient, textile technology thrived since the textile was a better thermal substitute for animal fur and the advent of sizing ensued. Before the Industrial Revolution, sizing and weaving were usually run in parallel and confined to coarse family craft. Women utilized homemade adhesive to lubricate natural fibers while spinning and weaving. In the late 18th century, the first power loom made its debut. Then, the sizing and weaving were generally developed into independent crafts done with separate machines. According to the record, the earliest sizing machine with comprehensive functions was invented by William Radcliffe and Thomas Johnson.

The sizing agent has evolved as well. In the beginning, people sized threads by virtue of plant starch and animal fat, such as sago, flour and mutton tallow. With the rise of synthetic chemicals, PVA was put into wide use for its additional functions, such as resistance to water. Currently, the textile industry takes eco-friendliness and sustainability into account while choosing the sizing material. 

Why Need Sizing in Fabric?

Promoting Weavability

Statistically, warps need to withstand repetitive stretching and bending more than 3000 times before being made into fabric. Moreover, the surface of a raw warp is by no means smooth, sticking out tiny fibers and hairs. Therefore, weaving raw warps directly gives rise to warp abrasion and breakage, and even induces stops of weaving machines.

The application of sizing enhances the quality of the weaving product and the efficiency of the weaving process. From the perspective of the warp, fibers are adhered and bonded and the surface is covered with a thin film after sizing. That is, it reinforces its cohesion and tensile strength. Given the weaving, the reduced hairiness and increased lubrication avoid knots and fraying, hence a better quality of the textile.

Adding Other Properties

In the modern textile industry, factories employ refined sizing recipes and advanced sizing processes to form an enduring film,  imparting some desirable properties to the fabric. It has been verified that fabrics can generate the following qualities with certain sizing techniques.

  • Weight change
  • Softness
  • Smoothness
  • Colorfastness
  • Easy handling
  • Eco-friendliness

Sizing Types and Sizing Methods

Types of Sizing 

According to the state of sizing solutions and warps, sizing falls into 2 types.

  • The impregnable sizing: Warps are soaked with sizing solution, internally and externally. 
  • The covering sizing: Only the surface of the warps is filmed with sizing solution. 

Types of Sizing Methods

Consequently, sizing has been developing and improving in terms of its machine and recipe. The textile industry now exits several different modes of sizing. Here is a brief list of common methods. 

  • Traditional method: Hank sizing, ball roll sizing, high pressure sizing, tape sizing (also called slasher sizing) and so on.
  • Improved method: prewetting sizing, solvent sizing, foam sizing, hot melt sizing and cold sizing.

Sizing Process

Preparing Proper Sizing Liquid: Above all, it is fundamental and crucial to make sizing liquid effective and available.

  • Recipe formulation based on warp structure, targeted application and processing environment.
  • Size cooking
  • Sizing liquid transportation
  • Detection and storage: It is stored in the size box after detention.

Forming a Preliminary Film

Warp sheets pass through a size applicator including the size box and squeeze rolls. They are dipped into the liquid and then squeezed to remove extra size. To guarantee each sheet receives sizing liquor of a suitable amount, an elaborate calculation needs to be done between the viscosity of sizing liquor and the pressure of squeeze rolls. 

Desiccating

Wet sheets are sent to the drying cylinder. The heated steam evaporates excess water. 

Waxing

Dry sheets pass over a waxing section to get additional lubrication. It lengthens the film’s validity and curtails hairness, facilitating weaving.

Splitting and Beaming

After the main sizing process, warp sheets reach the separation section and get appropriate finishing for easy waving.

FAQ

Is Starch the Same as Sizing?

Starch and sizing are two different conceptions. Starch itself refers to the substance found in potatoes, rice, etc. However, people sometimes refer to a type of craft through this word. It is a pretreatment before tailoring and stitching. You can add a layer of starch mix to improve the stiffness of the cloth and thus prevent shrinkage and slippery in the next process. On the other hand, sizing is a specialized and independent manufacturing procedure in fabric making. Additionally, it is conducted on the yarn in particular.

Conclusion

Have you got new knowledge about sizing? In conclusion,  sizing protects warps and revitalizes their wear characteristics and weaving performance. Through this technique, factories are capable of fabric production with more output, higher quality and lower consumption. 

Sinosilk offers a wide selection of silk fabrics and gives top priority to product quality. If you are looking for silk fabrics or silk products, you can not go wrong with us.

More Resources:

What is Woven Fabric – Source: Sinosilk

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