Pill Resistance | Fabric Pilling
Pilling is the appearance of bobbles on the fabric surface, the process consists of 3 stages;
1. Fuzz formation- fibres work loose and form a fuzz on the fabric surface
2. Pill formation- these loose fibres become entangled to form a pill
3. Wear off- The pill works it self loose or the anchor fibres snap and the pill becomes free of the fabric
2. Pill formation- these loose fibres become entangled to form a pill
3. Wear off- The pill works it self loose or the anchor fibres snap and the pill becomes free of the fabric
The occurrence of pills is due to a complex relationship between fibre, yarn and fabric structure, and the resultant properties of each will influence the formation of pills over the 3 stages. The phenomenon is more predominant in Staple Fibres; however it can occur in Filament? yarns as a result of weakened fibres abrading and breaking, creating loose surface fibres.
Fuzz formation is a result of fibre migration to the surface of the fabric, a mechanical action then results in the formation of pills through friction. The frictional force can come from the rubbing against a fabric of its own type, or another object such as jewellery or accessories which does not have to be textile. Factors which influence the fibres becoming loose are;
The fibres then have to amalgamate to form the pill, foreign matter can act as a nucleus for the pill and can contribute to the pills appearing a different colour to the fabric to which they are attached. The laundering process provides conditions for both fibres to work loose and work into a pill, as the mechanical agitation required to remove soiling allows for fibre migration and frictional contact. The pills then wear off the fabric either by the fibres still anchored within the yarn also working loose, or by them snapping, therefore breaking strength is a contributing factor, and strong fibres will require more energy to break them.
Pilling in fabrics became more of a problem when synthetic fibres were introduced and blended with natural, such as polyester, acrylic and nylon. This is because they have a higher strength than natural fibres, and therefore require more energy to break; their electrostatic properties also attract foreign matter, resulting in an unsightly appearance that is difficult to remove. The smooth surface texture and round Cross section? of synthetic fibres also provides a lower surface friction, enabling further their ability to migrate and form fuzz and then pills. The high strength of the fibres anchoring them on the fabric surface results in a higher level of abrasion required to remove them, which may take a longer period of time.
It is mainly the negative appearance associated with pilling which makes it an aesthetical problem in apparel applications, reduced strength and comfort can also be a consequence. Pilling is unsightly in garments, reducing the garment life by creating a negative visual appearance unacceptable to the consumer.
According to ISO 12945-1;2000 Fuzzing is the roughing up of or teasing out of the surface fibres from the fabric to produce a visible surface change.
Pills are ball shaped entanglements of fibres that are dense enough to cast a shadow.
Pilling is the generation of pills on the fabric surface.
There are a wide range of test standards relating to pilling, they aim to recreate and accelerate wear and/or laundering so results relate to the test environment and this does not always provide an accurate interpretation of actual wear conditions.
It is the assessment of pilling of which there is a range of research on. Currently this involves the subjective assessment undertaken by the tester; the sample is graded based on a description of what is viewed, which can vary with human perception.
International Standards;
ISO 12945 1:2000 Determination of fabric propensity to surface fuzzing and to pilling, Pilling box method.
ISO 12945 1:2000 Determination of fabric propensity to surface fuzzing and to pilling, Pilling box method.
ISO 12945 2:2000 Determination of fabric propensity to surface fuzzing and to pilling, Modified Martindale method
American Standards
ASTM D3512 / D3512M - 10e2 Standard Test Method for Pilling Resistance and Other Related Surface Changes of Textile Fabrics: Random Tumble Pilling Tester
ASTM D3512 / D3512M - 10e2 Standard Test Method for Pilling Resistance and Other Related Surface Changes of Textile Fabrics: Random Tumble Pilling Tester
ASTM D3511 / D3511M - 10e1 Standard Test Method for Pilling Resistance and Other Related Surface Changes of Textile Fabrics: Brush Pilling Tester
ASTM D3514 / D3514M - 10 Standard Test Method for Pilling Resistance and Other Related Surface Changes of Textile Fabrics: Elastomeric Pad
ASTM D4970 / D4970M - 10e1 Standard Test Method for Pilling Resistance and Other Related Surface Changes of Textile Fabrics: Martindale Tester
ASTM D3181 - 10 Standard Guide for Conducting Wear Tests on Textiles
How pills form has been outlined in the introduction. This section will focus on how to reduce the appearance of pills across the various stages involved in them becoming problematic.
The Pill Curve
The pill curve measures the time it takes for pill growth to reach its maximum point before wear off, the pill growth region will ultimately come to an end due to the exhaustion of loose fibres within the structure. From the diagram it is illustrated that occurring first is the formation of pills in the pill growth region, a state of equilibrium is then reached by which formation and break off rate are equal, before the rate at which pills are formed is overtaken by the rate at which they are lost, therefore the amount of pills reduce.
Taken from; Schindler, WD, 2004, Chemical Finishing of Textiles, USA; Woodhead Publishing.
To provide pill resistance it is required to either; reduce pill formation by reducing surface fuzz and its entanglement, and/or accelerate the speed at which the pills are lost, an approach may be taken to tackle an individual area or look at the whole system. To do so will require an in-depth understanding of the parameters involved at these stages in terms of selected fibre, yarn, fabric and finish.
From the process by which pills are formed it can be indentified the areas which can be targeted;
1. Fuzz formation
2. Entanglement
3. Wear off
2. Entanglement
3. Wear off
Furthermore at each of these stages the following parameters can be addressed;
• Fibre selection
• Yarn selection
• Fabric Structure
• Finish (mechanical or chemical)
• Yarn selection
• Fabric Structure
• Finish (mechanical or chemical)
The conditions of use will also determine the extent to which pilling occurs, variables such as force, duration, mechanical action, surface texture, Relative humidity?/Moisture content? will all play a role in how the fabric reacts based on its structural parameters.
The affect of laundering on textiles can have a positive or negative impact on pilling and this is entirely due to the materials used and structure of the textile. In some instances tumble drying can reduce pill build up by removal of loose fibres free from the fabric, therefore not enabling them to form pills, however if fibres are not fully separated they can remain on the surface where they may form pills, having the opposite affect. Again fabric softener can have a negative affect by reducing friction leading to a higher migration of fibre, or it can act as a Lubricant? on the fibre, reducing damage by abrasion, abrasion that may result in loose fibres creating surface fuzz.
The opposing affects observed on different fabrics as a result of the same process further illustrates the complexity of engineering pill resistance. It is clear that there are a wide range of actions which can be taken, some of these actions are conflicting, and therefore the design process requires a careful balancing act to produce an outcome to meet requirements.
Factors commonly considered are Twist? usually intended to be cut or stretch-broken for use in staple fibre or top form.">Tow?.">Crimp?, Twist?, Cross section? and surface texture in relation to the frictional forces which hold fibres in place, ring spun yarns are generally more resistant to pilling. Finishes such as; singeing, heat setting, steaming and shearing prevent/minimise fuzz formation. Although a key approach has been to enable quick wear off, therefore synthetic fibres have been engineered to be weaker so the anchor fibres require less energy to break and remove the pill from the fabric surface.
The TEGEWA nomenclature of Textile Auxiliaries does not outline a specific category of anti-pilling products, this is representative of the large variety of parameters which contribute to pilling, and these are further complicated by which stage of the process, or part of the problem they work to eliminate. Finishes can be applied to bind the fibres in the fabric and prevent fuzz formation, or prevent adherence of fibres or foreign materials to the surface through static attraction.
