Loose fibers exiting the surface of the fabric are agglomerated by friction and form a bundle when the garments are used and washed. This results in a garment worn and unpleasant to the eye. In the formation of pilling, the fineness, length, bending strength, tensile strength and interfiber friction force of the fibers, as well as the structural properties of the yarn and fabric and the effect of other processes applied to the fabric are very high.

In fact, all natural, man-made and synthetic fibers tend to be pilling, although they differ in yarn properties used in the fabric weaving. In the cross-sectional area of ​​the yarn consisting of fine fibers, the number of fibers to cause fluff is higher. As the fibers thicken, pilling tendency decreases. In addition, if the fibers are too long, the pilling tendency decreases.

Beads formed on fabrics made of fibers with low resistance to tensile and repeated bending easily separate from the fabric surface. The life of these beads is short. Therefore, wool is a less beaded fiber.

There are many devices that test pilling strength in fabrics. The main differences between the most preferred test devices are divided into three points:

• Type of friction material
• Counter-action against friction material
• The amount of force applied to the sample

The most commonly used test devices by laboratories today are: ICI Pilling Test Box, Random Tumble Pilling Tester, Martindale Abrasion Tester, Elastomeric Cushion Base Method and Brush Pilling Tester.

Beading tests carried out by authorized laboratories using Martindale test equipment are based on the following standards:

• TS EN ISO 12945-2 Textiles - Determination of surface feathering and pilling tendency in fabrics - Part 2: Improved Martindale method
• ASTM D 4970 Standard test method for the pilling susceptibility of textile fabrics to resistance and other related surface changes: Martindale Tester
• SN198 525 Modified Martindale method