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1. Scope and Application
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1. Scope and Application
CAN CGSB 4.2 No. 68-2004 (2013), part of the Canadian General Standards Board (CGSB) 4.2 series of textile test methods, specifies a random tumble pilling procedure for assessing the resistance of textile fabrics to pilling and other related surface changes. This method is widely used in the Canadian textile industry for quality control and product development.
The test method is applicable to most woven and knitted fabrics, including those made from natural, synthetic, and blended fibres. It simulates the abrasive action and pill formation encountered during normal wear by tumbling fabric specimens in a cylindrical chamber lined with specific materials. The standard provides two test options — Type A (cork liner) and Type B (rubber liner) — to accommodate different fabric structures and end-use requirements.
Tip: The choice of liner type depends on the fabric’s tendency to generate lint. Type A is recommended for fabrics that produce loose fibres, while Type B is used for fabrics that shed minimal lint. Always refer to the product specification or client agreement to select the appropriate option.
2. Technical Requirements and Test Method
2.1 Apparatus and Equipment
The key apparatus required includes:
- Random Tumble Pilling Tester — A motor-driven cylindrical chamber, typically with two or four compartments, capable of rotating at 1200 ± 60 r/min.
- Liners — Either cork (Type A) or rubber (Type B), cut to fit the chamber walls securely.
- Specimen Mounting Tubes — Polyurethane or similar tubes, approximately 80 mm in diameter, onto which fabric specimens are fastened.
- Compressed Air Supply — Regulated to 0.21 MPa (30 psi) to introduce lint into the chamber.
- Vacuum System — For removal of loose fibres after the test.
- Evaluation Area — A standard viewing box or light booth with daylight (D65) illumination for rating.
- Photographic Standards — Reference images showing pilling intensity from Grade 5 (no change) to Grade 1 (very severe pilling).
| Parameter | Type A (Cork Liner) | Type B (Rubber Liner) |
|---|---|---|
| Specimen size | 105 mm × 105 mm | 105 mm × 105 mm |
| Number of specimens per sample | 4 (two per tube, back-to-back) | 4 (two per tube, back-to-back) |
| Tumbling time | 60 min ± 1 min | 30 min ± 30 s |
| Chamber air pressure | 0.21 MPa (30 psi) | 0.21 MPa (30 psi) |
| Lint control | Lint suction after test | Lint suction after test |
| Evaluation method | Comparison with 5-grade photographic standards* | Comparison with 5-grade photographic standards* |
| *Grades: 5 = no change, 4 = slight pilling, 3 = moderate pilling, 2 = severe pilling, 1 = very severe pilling. | ||
2.2 Specimen Preparation
Conditioning: All test specimens must be conditioned in a standard atmosphere (21 ± 1 °C, 65 ± 2 % relative humidity) for at least 4 hours prior to testing. Cut five specimens per sample (four for testing and one spare) from areas representative of the fabric, avoiding creases, folds, and selvedges.
Mounting: Each specimen is folded in half (face side out) and fastened around a mounting tube using a fastener tape or adhesive. The two edges are aligned so that the fabric surface is uniformly exposed. The mounted tubes are then placed into the test chamber.
2.3 Test Procedure
- Ensure the chamber is clean and the appropriate liner is installed without wrinkles or gaps.
- Place the two mounted tubes into the chamber, ensuring they are positioned symmetrically for balanced tumbling.
- Close the chamber lid and start the rotation. Simultaneously, introduce compressed air to supply the prescribed air pressure for the first 60 seconds of the test.
- Tumble for the specified duration (60 min for Type A, 30 min for Type B). Do not open the chamber during the test.
- After the test, remove the specimens and vacuum them to remove loose lint. Condition them again for at least 1 hour before evaluation.
- Each specimen is rated independently by at least two observers under standardised lighting by comparing with the photographic standards. The arithmetic mean of all ratings (rounded to 0.1) is reported as the pilling resistance grade.
Common Pitfall: Using liners beyond their recommended life (typically 50 tests for cork, 100 for rubber) leads to inconsistent abrasion. Always replace liners according to the manufacturer’s instructions or when visible wear appears.
3. Implementation Highlights
To obtain repeatable and reproducible results with CAN CGSB 4.2 No. 68-2004 (2013), several practical considerations should be observed:
- Calibration of Apparatus: Periodically verify the tester’s rotation speed, air pressure regulator accuracy, and chamber seal integrity. Many commercial laboratories perform daily verification using a reference fabric to confirm consistent results.
- Specimen Marking: Use a permanent marker to label the back of each specimen with sample identification and orientation. This prevents confusion during rating.
- Liner Uniformity: Cork liners are natural products and may vary in thickness and density. Purchasing liners from reputable sources and measuring thickness before each test helps minimise variability.
- Evaluation Consistency: Observers should be trained annually using the same set of reference photographs. Laboratories often use a panel of three observers and report the median rating for increased objectivity.
Best Practice: For fabrics that are prone to fuzzing rather than pilling, consider pre-treating the specimens with a standard washing cycle (per CAN CGSB 4.2 No. 30) to remove surface fibres before tumbling. This often provides a more realistic simulation of in-use performance.
4. Compliance and Reporting Notes
Compliance with CAN CGSB 4.2 No. 68-2004 (2013) requires strict adherence to the specified procedures and documentation. The following elements must be included in the test report:
- Reference to this standard (CAN CGSB 4.2 No. 68-2004 (2013)) and the version year.
- Liner type used (A or B).
- Details of the sample (e.g., fabric construction, fibre content, finish).
- Number of specimens tested.
- Individual specimen ratings and the computed mean grade.
- Any deviations from the standard procedure (e.g., alternative conditioning times, liner substitution).
- Date of test and name of testing laboratory.
Warning: Tests performed without the specified pre‑conditioning or with incorrect liners are not compliant with CAN CGSB 4.2 No. 68-2004 (2013). Such results cannot be reported as “CGSB compliant” and may lead to product rejection if submitted for certification.
The standard also notes that in case of dispute, the cork liner method (Type A) shall be considered the referee method unless otherwise agreed upon by the interested parties.
Frequently Asked Questions
Q: What is the difference between Type A and Type B liners in CAN CGSB 4.2 No. 68-2004 (2013)?
A: Type A uses cork liners, which are mildly abrasive and allow moderate lint generation; it is typically used for fabrics that produce loose fibres (e.g., wool, fleece). Type B uses rubber liners, which are more abrasive and generate less lint; it is better suited for tightly constructed fabrics such as polyester or nylon knits that shed minimal fibres.
A: Type A uses cork liners, which are mildly abrasive and allow moderate lint generation; it is typically used for fabrics that produce loose fibres (e.g., wool, fleece). Type B uses rubber liners, which are more abrasive and generate less lint; it is better suited for tightly constructed fabrics such as polyester or nylon knits that shed minimal fibres.
Q: Can this random tumble pilling method be applied to all textile fabrics?
A: The standard is applicable to most woven and knitted fabrics. However, it is not recommended for fabrics that are very thick (e.g., upholstery) or that have a surface finish that can be removed by the liners (e.g., flocked or metallic coatings). In such cases, alternative methods like the Martindale pilling test may be more appropriate.
A: The standard is applicable to most woven and knitted fabrics. However, it is not recommended for fabrics that are very thick (e.g., upholstery) or that have a surface finish that can be removed by the liners (e.g., flocked or metallic coatings). In such cases, alternative methods like the Martindale pilling test may be more appropriate.
Q: How is the pilling rating determined objectively?
A: After tumbling, each specimen is compared with a set of five photographic reference standards (Grades 5 to 1). Grading is performed under standardised lighting (D65) by at least two trained observers. The specimen’s rating corresponds to the photograph that most closely matches the appearance of the fabric surface in terms of pill density, size, and overall change.
A: After tumbling, each specimen is compared with a set of five photographic reference standards (Grades 5 to 1). Grading is performed under standardised lighting (D65) by at least two trained observers. The specimen’s rating corresponds to the photograph that most closely matches the appearance of the fabric surface in terms of pill density, size, and overall change.
Q: What are the most common causes of non-reproducible test results?
A: Variability often arises from worn or inconsistent liners, improper specimen mounting (loose fabric or uneven tension), failure to control air pressure accurately, and subjective rating differences among observers. Regular calibration, use of reference fabrics, and annual observer training help reduce these issues.
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A: Variability often arises from worn or inconsistent liners, improper specimen mounting (loose fabric or uneven tension), failure to control air pressure accurately, and subjective rating differences among observers. Regular calibration, use of reference fabrics, and annual observer training help reduce these issues.