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Introduction
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Introduction
CAN/CGSB-4.2 No. 78.1-2001 (2013) is a Canadian national standard belonging to the Textile Test Methods series (CAN/CGSB-4.2). It specifies a hydrostatic pressure test method for determining the resistance of fabrics to water penetration. The standard is technically equivalent to ISO 811:1981 and reaffirmed in 2013, confirming its continued relevance for evaluating the waterproofness of textile materials used in protective clothing, tarpaulins, tents, and other technical textiles.
Scope and Application
This standard applies to any textile fabric, whether woven, knitted, nonwoven, or coated, that is intended to resist water penetration under pressure. The test simulates exposure to water under increasing pressure on one face of the fabric, measuring the pressure at which water first penetrates (hydrostatic head) or the rate of water passage at a given pressure.
Tip: This method is widely adopted by Canadian manufacturers for quality control of rainwear, outdoor gear, and industrial membranes. It is often referenced alongside ASTM D751 and AATCC 127.
The standard is particularly important for compliance with Canadian regulatory requirements for personal protective equipment (PPE) and for product performance labeling.
Technical Requirements and Test Methodology
Test Principle
A specimen is clamped over a water reservoir. Water pressure is increased at a controlled rate until three droplets of water appear on the opposite surface. The hydrostatic pressure at that moment is recorded in centimetres of water column (cm H₂O) or millibars (mbar).
Apparatus and Conditions
The testing apparatus must include a water reservoir with a clamping mechanism that prevents edge leakage, a pressure gauge, and a means to control the rate of pressure increase. Key parameters are:
| Parameter | Requirement |
|---|---|
| Water temperature | 20 ± 2 °C |
| Rate of pressure increase | 1.0 ± 0.05 kPa/min (equivalent to approximately 10 cm H₂O/min) |
| Specimen conditioning | Standard atmosphere: 20 ± 2 °C, 65 ± 4% RH, minimum 24 h |
| Specimen size (exposed area) | 100 cm² (circular test area with 113 mm diameter) |
| Number of specimens | At least 5 (test both faces if asymmetric) |
| Reporting units | cm H₂O or kPa, with the first penetration pressure recorded |
Important: The pressure increase rate must be carefully maintained. Deviations beyond ±5 % may significantly alter results, especially for coated fabrics.
Procedure
After conditioning, the specimen is clamped with the side to be tested facing the water. Pressure is increased steadily until three distinct droplets appear on the opposite surface. If leakage occurs at the clamp edges, the test is invalid. The hydrostatic head is recorded in cm H₂O. For high-performance materials, testing may continue until a specified pressure is held without penetration.
Implementation Highlights
To ensure reproducible results, laboratories must carefully control the conditioning environment and water quality (distilled or deionized water). The clamping mechanism must be checked regularly for wear to avoid false failures. The standard allows the use of alternative pressure rates if stated in the report, but the standard rate is mandatory for conformity assessment.
Best Practice: For materials with very high water resistance (e.g., >200 cm H₂O), use a digital pressure sensor with appropriate range (0–500 cm H₂O) and calibrate annually.
Results can be sensitive to fabric anisotropies and surface treatments. It is recommended to test both directions (warp/weft) and both sides if the fabric is asymmetrical. The mean hydrostatic head and coefficient of variation are normally reported.
Compliance and Certification Notes
CAN/CGSB-4.2 No. 78.1-2001 (2013) is a reaffirmed standard, meaning its technical content remains current without changes. It is widely referenced in Canadian procurement contracts for government purchases of waterproof textiles, such as for military, firefighting, and law enforcement gear.
To claim compliance, a testing laboratory must be accredited to ISO/IEC 17025 and include this standard in its scope. The report must clearly state the standard designation, test conditions, individual results, and statistical summary. Products meeting a defined minimum hydrostatic head (e.g., 150 cm H₂O for moderate waterproofness) can be labeled accordingly.
Common Pitfall: Using water with high dissolved solids or insufficient deaeration can cause micro‑bubble formation on the fabric surface, leading to premature penetration readings. Always use freshly deaerated distilled water.
Users should note that this method does not measure water repellency or resistance to dynamic impact (e.g., rain) – it is a static pressure test. For a complete waterproofness assessment, combine it with a spray test (e.g., AATCC 22) or a rain test (e.g., ISO 22958).
Frequently Asked Questions
Q: Is CAN/CGSB-4.2 No. 78.1-2001 (2013) identical to ISO 811?
A: Yes, this standard is the Canadian adoption of ISO 811:1981 without technical deviations. Laboratories using either standard can expect equivalent results provided all test conditions are matched.
A: Yes, this standard is the Canadian adoption of ISO 811:1981 without technical deviations. Laboratories using either standard can expect equivalent results provided all test conditions are matched.
Q: Can this method be used for coated fabrics?
A: Yes, but special attention must be paid to the clamping to avoid leakage at the edges. For coated fabrics, the test area must be free of pinholes. The method is suitable for waterproof coatings as long as the coating is on the pressure side.
A: Yes, but special attention must be paid to the clamping to avoid leakage at the edges. For coated fabrics, the test area must be free of pinholes. The method is suitable for waterproof coatings as long as the coating is on the pressure side.
Q: What is the difference between hydrostatic head and water repellency?
A: Hydrostatic head measures the pressure resistance to water penetration, while water repellency (e.g., spray rating) assesses the fabric’s ability to shed water without absorbing it. Both are complementary but measure different performance aspects.
A: Hydrostatic head measures the pressure resistance to water penetration, while water repellency (e.g., spray rating) assesses the fabric’s ability to shed water without absorbing it. Both are complementary but measure different performance aspects.
Q: Has the standard been updated since 2013?
A: As of 2026, this standard remains current in its 2013 reaffirmed version. The CGSB reviews all standards every five years; no newer version has been published yet. Always verify with the official catalogue for the latest status.
A: As of 2026, this standard remains current in its 2013 reaffirmed version. The CGSB reviews all standards every five years; no newer version has been published yet. Always verify with the official catalogue for the latest status.
© 2026 Technical Standards Review. This article is for informational purposes and does not replace the official standard. For certification, refer to the latest version of CAN/CGSB-4.2 No. 78.1-2001 (2013) published by the Canadian General Standards Board.
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