Fabric strength is determined by three characteristics: pilling, abrasion, and snagging. Using a Martindale tester, ASTM D4970 examines surface changes in textile fabrics, including pilling resistance. This overview by a lab technician will cover all the points needed to perform this test.
How to Define Pilling?
Pilling refers to the formation of tiny, fluffy fiber balls on the surface of a cloth. It should not be confused with abrasion, which is the wear and tear of fabric caused by friction with another substance. Friction between the fabric and another object causes the fabric to pill. Laundering also plays a significant role, and care should be taken. If it’s feasible, turning clothing inside out is an easy approach to reduce pilling.
Fabric pilling can also occur through rubbing during wear. Pilling can be removed from fabric by hand or by some shaver, but abrasion can lead to tears and holes. Generally, synthetic fibers pill more than natural fibers. The synthetic fibers serve as an anchor for the pill to form because of their lengthy fiber lengths and greater strength.
Fabric Pilling Test Method
- Martindale test method
- Pilling box method
- Circular locus method
Standards like ISO 12945-2 and ASTM D4970 are frequently used for pilling testing.
An extensive overview of the Martindale test method (ASTM D4970) for fabric pilling test is provided here.
What is ASTM D4970
The American Martindale method for utilizing a Martindale tester to measure pilling resistance is ASTM D 4970. A circular piece fastened to the specimen holder of the Martindale Tester is rubbed against a standard fabric in a motion that creates a Lissajous figure at a predetermined rate and pressure. A perpendicular central axis to the sample plane allows the sample to spin freely. Following a specific rubbing phase, a visual description is used to assess the sample for abrasion, pilling, or felting.
Figure 1 depicts the Lissajous motion, a graph created by varying the motion from a circle to a progressively shrinking ellipse until it becomes a straight line. The motion is then repeated diagonally, asymptotically, from this line to a widened ellipse until it becomes a circle. The instrument has a pre-settable counting device to track the number of revolutions for each movement. A single rotation represents a single friction, while a whole Lissajous pattern comprises 16 frictions.
The Martindale pilling tester can also be used for abrasion testing by changing the applied pressure.
Textile Testing Equipment for ASTM D4970
- Martindale Tester
- Standard felt: weight 750 ± 50g/m2 (22 ± 1.5oz/yd2), thickness 3 ± 0.3mm (0.12 ± 0.01in.)
- Light Box containing C.W.F light source (Cool white fluorescent tube)
- Fabric cutters or fabric punches have diameters of 38mm (1.5in) and 140mm (5.5in).
- Photographic standards (A set of five pictures, numbered 1 through 5, depicting differing degrees of pilling from “very severe pilling” to “no pilling”).
- A rating fabric is a collection of well-preserved, previously tested pieces of a certain fabric type. These specimens demonstrate varying levels of pilling.
Test specimens’ preparation for ASTM D4970
- Lay the fabric or garment flat on a surface.
- Take the specimens evenly spaced across the width of the fabric or from 2 different panels in a garment. Avoid areas with creases and distortions. Also, avoid cutting specimens nearer to selvage.
- Cut a pair of circular specimens, with one pair being 38mm(1.5in.) in diameter and the other 140mm (5.5 in) in diameter.
- Condition specimens at standard atmospheric conditions for about 4 hours. i.e. 21 ± 1°C (70 ± 20°F) and 65% relative humidity.
Testing Procedure for ASTM D4970
- Place the standard felt with bigger diameter 140mm(5.5in.) on bottom plate and mount the fabric over it.
- Similarly, place the standard felt with smaller diameter 38mm(1.5in.) on top plate and mount the fabric over it.
- Make sure the face of the fabric should be exposed for both specimens.
- Now, insert the mounting weight of approximately 3Kpa (0.44psi) to give pressure on the larger specimen.
- Give the command for 100 movements and start the Martindale tester.
Conclusion and Fabric Lab Test Report
- Take the 38-mm(1.5in.) disk specimen out for examination.
- Evaluate the specimen by comparing it with photographic standards or with suitable fabric.
- Rate the fabric from 5 to 1 (no pilling to very severe).
Where, - 5 – No pilling
4 – Slight Pilling
3 – Moderate Pilling
2 – Severe Pilling
1 – Very Severe Pilling - Similarly, repeat the process as desired for the average result.
Fabric Lab Test Report Contains
- State details about the specimen’s material. (e.g., knit or woven, yarn type, weave, etc.)
- If fabric was washed or dry cleaned before testing, state the conditions.
- Clearly states the number of movements and rating standards used (photographic or fabric).
- Write about each specimen rating individually and then their average rating.
- State that the test was performed according to ASTM D4970.
Fabric Abrasion and PillingFAQs
1. How do you tell if a fabric will pill?
A fabric surface with more protruding fiber, like wool, has a higher chance of pilling.
2. Is pilling a sign of bad quality?
It is usual for textiles to pill; it’s like an initial shedding. Generally, pilling will occur after initial usage, within the first 4-6 months, and can be successfully removed on-site with a quality lint shaver.
3. What causes pilling in clothes?
Clothes fabric fibers tangle to form a bead-type projection on the fabric’s surface, thus leading to pilling.
4. Does the composition of a fabric have any effect on pilling?
Yes, of course. Typically, synthetic fibers show more pilling than cotton. This is because they have longer strands of fiber than cotton and do not easily break upon friction. This leads to bead formation.
5. Do you have any advice on avoiding or reducing pilling?
Generally, we can reduce the pilling of fabric by handling it with care. Try to wash these fabrics inside out so that their surface has minimum friction with each other. Avoid fabric rubbing with itself or other surfaces.
6. What are the standards for fabric pilling testing?
ISO 12945-2 and ASTM D4970 are frequently used for pilling testing.
Related Resources
ASTM D4970/ISO 12945.2 Martindale Abrasion & Pilling Tester YG(B)401T
A Complete Guide to ASTM D4970 ISO 12945 Martindale Pilling Test Method
ASTM D4970/ISO 12945.2 Pilling & Abrasion Tester YG(B)401C
ASTM D4970/ISO12945.2 Martindale Abrasion & Pilling Tester YG(B)401GC