1. Scope and Application

“content”: “

1. Scope and Application

CAN CGSB 4.2 No. 33-94 (2013) is a Canadian standard developed by the Canadian General Standards Board (CGSB) that specifies a laboratory test method for determining the resistance of textile fabrics to water absorption when subjected to immersion in distilled water. The method, commonly referred to as the Immersion Test, measures the mass of water taken up by a dry fabric specimen after being immersed for a specified period under controlled conditions.

This standard applies to woven, knitted, and nonwoven fabrics, including those treated with water-repellent finishes. It is primarily used for evaluating the effectiveness of hydrophobic treatments and for quality control in products such as rainwear, tents, outerwear, and industrial textiles that require resistance to water penetration.

The test method is not intended to simulate the action of rain or dynamic water exposure; rather, it provides a reproducible static immersion condition that quantifies the inherent absorbency of the fabric structure and surface treatment. The current version, reaffirmed in 2013, remains the authoritative reference for water absorption testing in the Canadian textile sector.

2. Technical Requirements

2.1 Apparatus and Materials

The following equipment is required to perform the test in accordance with CAN CGSB 4.2 No. 33-94 (2013):

• A chemical balance capable of weighing to 0.01 g.
• A beaker, glass or stainless steel, of sufficient capacity (typically 1 L) to hold the specimen without folding.
• Distilled or deionized water maintained at 20 ± 2 °C.
• Timer or stopwatch accurate to ±0.5 seconds.
• Forceps or tongs for handling the wet specimen.
• Standard textile conditioning environment (20 ± 2 °C, 65 ± 4% RH) for pre-conditioning.
• A bowl or drain rack to support the specimen after removal from water.

2.2 Test Specimens

From each sample, cut five specimens of dimensions 200 mm × 200 mm, or any size agreed upon as long as area is known. The specimens should be conditioned at standard atmosphere (20 ± 2 °C, 65 ± 4% RH) for at least 24 hours before testing.

2.3 Procedure

1. Weigh each conditioned specimen to the nearest 0.01 g (dry mass, M_d).
2. Immerse the specimen completely in distilled water at 20 ± 2 °C for 5 ± 0.25 minutes. Ensure the specimen is free to move and not folded.
3. After the immersion time, remove the specimen carefully using forceps. Hold it in a vertical position for 10 ± 2 seconds to allow excess water to drain.
4. Weigh the specimen immediately to the nearest 0.01 g (wet mass, M_w).
5. Discard the specimen; do not reuse.

2.4 Calculation and Expression of Results

Calculate the water absorption A as a percentage of dry mass:

Where:

• A = water absorption percentage
• M_w = wet mass (g)
• M_d = dry mass (g)

Report the mean of the five individual results and the standard deviation. Also note any deviations from the standard procedure (e.g., alternative immersion time).

3. Interpretation of Results

Water absorption values are inversely related to the effectiveness of a water‑repellent finish. Typical interpretation guidelines for general textile use include:

The values above are indicative only. The standard itself does not assign pass/fail criteria; specifications must be negotiated between purchaser and supplier. Repeatability can be influenced by fabric structure, yarn composition, and finish type.

4. Implementation Highlights

4.1 Sample Conditioning and Handling

To obtain reliable results, the following practices are essential:

• Condition specimens for at least 24 hours in a standard atmosphere to minimize moisture content variability.
• Use clean forceps and handle wet specimens carefully to avoid water droplet loss or absorption.
• Weigh the wet mass within 30 seconds of removal to prevent evaporation.
• Perform the test in a controlled humidity environment (65 ± 4% RH) to maintain standard conditions.

4.2 Precision and Bias

CAN CGSB 4.2 No. 33-94 (2013) includes precision data based on interlaboratory round‑robin tests. Within‑laboratory repeatability (r) is typically 1.0–1.5%, while reproducibility (R) is around 2.5–3.0% for most fabrics. The standard does not provide a bias statement, as the method is a direct measurement of water uptake.

4.3 Modifications and Alternative Conditions

The standard permits variations, such as:

• Alternative immersion times (15 min, 30 min, etc.)
• Use of a specified wetting agent if agreed
• Testing of multiple specimen sizes

When modifications are made, they must be clearly stated in the test report. The standard requires that any deviation be noted and that results from modified procedures are not directly comparable to the standard method.

5. Compliance and Accreditation

Laboratories performing this test method should be accredited to ISO/IEC 17025 by a recognized accreditation body. Specifically:

• The laboratory must demonstrate competence in textile testing and employ personnel trained in water absorption testing.
• All balances and timers must be calibrated with documented traceability to SI units.
• A quality control program using standard reference fabrics (e.g., CGSB Standard Reference Material) is recommended.
• Records of conditioning, water temperature, and environmental conditions during the test must be maintained.

6. Frequently Asked Questions