Pilling refers to the small pieces or balls of fiber that accumulate on the surface of a textile. Pilling is a common problem encountered in both fabrics and finished garments. Pilling occurs when loose fibers and fiber ends accumulate at the surface of a textile. After a while, these fibers become entangled and start to form small knots or balls. Eventually, the pill might grow in size due to accumulation of more and more fibers. These knots do not immediately come off the fabric because the entangled fibers are anchored to other fibers that are still attached to the fabric’s interior. As long as the pills are anchored strongly enough, they will not easily detach from the fabric surface by themselves.

Pilling is a process that happens over time and can be divided into four different phases including: accumulation, entanglement, growth and detachment.

Phase 1: Loose Fiber Accumulation
Pilling starts when loose fibers and protruding fiber ends accumulate at the surface of a fabric.

Phase 2: Entanglement
After a while, the first fibers become entangled with each other and start to form little knots. At this point, the pill and/or fuzz is still small in size.

Phase 3: Pill Growth
Later on the pill grows in size as more and more protruding fiber ends and loose fibers become entangled. Now, the small balls of fiber become better visible.

Phase 4: Wear-Off or Detachment
Pill detachment either happens naturally (i.e. wear-off without interference from direct outside forces) or manually (e.g. removal by specific devices such as lint shavers). Eventually, most pills will wear off when the force of the pill exceeds the strength of the anchor. Note that not all pills will detach or wear-off by themselves.

Pilling is mainly caused by friction, meaning that pilling tends to occur when the fabric or garment rubs against other surfaces and wears down. The result is an abrasive effect that leads to more loose fiber ends and fiber entanglement. The two main sources of friction are encountered when a garment is worn and when it is washed.

Wearing
Not all areas of a garment endure a similar amount of stress. Especially high-friction areas such as the chest, shoulders, elbows, crotch and cuffs are more inclined to pill. These areas tend to rub the most against other surfaces (e.g. against a chair while sitting or while carrying a heavy shoulder bag). In addition, the environment and personal wearing habits of the wearer also influence pilling.

Garment Care
Besides wearing, garment care can also influence the chances of pilling. Combinations of water, heat, detergents and mechanical action (e.g. washing machine cycles) can cause pilling. Learning and maintaining good wear and care habits is crucial for minimizing the chances that a garment will pill. This includes avoiding:

• Washing garments too often.
• Washing on wrong temperatures.
• Washing garments together with abrasive or sharp objects (e.g. keys or chains).
• Washing too many garments at the same time.
• Using the wrong washing cycle.
• Using too much laundry detergent and/or softener.

Since pilling is a complex process, the impact of friction on a fabric is related to multiple factors that can make a textile more or less prone to pilling.

Fiber Type
Even though basically all fibers pill to some extent, some types of fiber are less inclined to pill than others. Therefore, the type of fiber used in a textile influences pilling. For instance, shorter and finer fibers tend to pill more quickly compared to larger, coarse fibers. It happens because shorter fibers have more other fibers in their vicinity to attach to. Additionally, when fibers blended together and the blend clearly has a weaker fiber, the weaker fiber tends to wear down the quickest and break first, causing its loose ends to pill. Consequently, the stronger fiber serves as the main anchor for the loose ends to attach to.

Yarn Properties
The yarns used to construct a fabric, and eventually a garment, influence the fabric’s propensity to pill. For example, yarns with a lower twist or hairy fibers tend to pill more easily.

Dyeing
Dyeing also influences pilling as dye alters the strength of the fiber and impact its hairiness.

Scouring and Milling
Scouring and milling tends to make fibers more hairy and therefore increases the textile’s propensity to pill.

Fabric Density
In general, the denser a fabric is, the less likely it will pill. Usually, softer and airier fabrics tend to pill more quickly.

As mentioned before, pilling is a complex process that knows many influences. In the life cycle of a garment or textile, four phases can be distinguished, during which measures are taken to control and decrease the chances of pill formation.

Textile Construction
The construction phase is an aspect over which consumers have little to no influence. However, already during the construction process of a textile, multiple anti-pilling processes can be undertaken to avoid pill formation later on in the life of the textile. These processes include:

• Increased friction between fibers
• Increased fiber to fiber bonding
• Weaking of the surface fibers.

The challenge with some of the anti-pilling processes is that they come with a tradeoff between on the one hand fabric handle, fluidity and/or softness and pill performance on the other hand.

Garment Construction
During the design of a garment, significant thought goes into elements such as selection of proper materials, seam construction, use of fasteners, application of trimmings, and much more. Making proper choices during the design phase includes for example:

• Smart placement of zippers, Velcro, hooks, buttons or other fasteners.
• Careful placement of beads, stones, chains and other trimmings.
• Providing proper garment care instructions.
• Avoiding labels with a sharp edge.
  
  

Wearing and caring
As mentioned above, the wearing habits and environment of the wearer have a tremendous impact on pill formation. Some additional wearing and caring techniques provide some control over pilling such as:

• Always follow the laundry care instructions and do not exceed them.
• Using washing bags to protect delicate items.
• Wash on gentle cycles or by hand.
• Wash garments inside out. This does not avoid pill formation but by washing inside out, pilling tends to occur on the inside rather than on the outside of the garment and therefore won’t be visible when you wear it.
• Fasten all zippers, buttons, hooks or other sharp fasteners as these items are sometimes hard and can cause the fibers to come loose.
• Avoid using a tumbled dryer unnecessarily.
• Avoid prolonged friction between the elbows and tables.
  
  

Pill removal
Keeping your pieces well-maintained goes a long way to avoid pilling. However, in case pilling does occur, there are a few tools available that can help to remove the pills. The generally more suitable tools include:

• Sweater comb
• Sweater stone
• Electric pill remover

A small sidenote and disclaimer, be very careful when using any pill removal tool as in some cases it can only make things worse and create permanent damage to your pieces. It is easy to exercise too much strength which will only damage the fabric. Additionally, be extra careful when dealing with knits and/or other loose fabrics as these get damaged more easily.

There are multiple tools and machine available to test a textile for pilling. For example, pilling can be tested via methods such as abrasion tests or tumbling tests. Samples of textile are checked for pilling and can be evaluated by looking at important parameters such as:

• Number of pills
• Mean pill area
• Total pill area
• Density of the pilling

After testing, the pill formation is analyzed and evaluated along a 5-point scale where the first grade means very strong pilling formation and the fifth grade denotes no pill formation in the sample after testing. In other words, the higher the score, the better the fabric resists pill formation and fuzzing. The samples can be graded as:

Grade 5 – No visible change
No visible change has taken place after testing the textile.

Grade 4 – Slight change
A slight fuzz occurs on the surface of the textile.

Grade 3 – Moderate change
Moderate fuzzing is visible and/or some isolated pills have formed on the surface of the textile.

Grade 2 – Significant change
Noticeable fuzzing and/or pilling occurs on the surface of the textile. 

Grade 1 – Severe change
Dense and and/or pilling occurs all over the surface of the fabric of the textile.

Pilling refers to the formation of small pieces or balls of fiber that accumulate at the surface of a textile. Pilling is a complex process that builds up over time and can be categorized into four distinct phases:

• Accumulation, loose fibers and fiber ends accumulate at the surface of the fabric.
• Entanglement, the first loose fibers and fiber ends become entangled.
• Growth, the pill grows in size as more fibers become entangled.
• Detachment, the pill detaches from the surface of the fabric.

Even though pills do not necessarily have an immediate impact the functionality of a fabric, it is usually regarded as an unwanted effect that can become problematic when a lot of pilling occurs in the same spot. One of the main causes of pilling is friction that occurs during wearing and garment care. A textile might be more or less prone to pilling, depending on different characteristics of the textile such fiber type, yarn type and fabric density. However, the wearing habits and environment of the wearer also have an influence on pilling.