AATCC TM127 Hydrostatic Pressure Test: Waterproof Fabric Buyer’s Guide
AATCC TM127 is commonly used to evaluate how well a textile resists water penetration under hydrostatic pressure. It is relevant to waterproof and water-resistant fabrics used for rainwear, outdoor equipment, tents, bags, covers and other products exposed to wet conditions.
The method provides useful material-level data, but a result should always be read together with the tested construction, pressure application conditions, specimen orientation, conditioning and agreed endpoint.
A high result from one fabric does not automatically prove that a finished jacket, tent or bag will remain waterproof. Seams, stitching, zippers, vents, coatings, laminations and manufacturing quality can all influence finished-product performance.
What Is AATCC TM127?
The current edition listed by AATCC is AATCC TM127-2017(2018)e, Test Method for Water Resistance: Hydrostatic Pressure.
The method applies to different textile constructions, including fabrics that have received water-resistant or water-repellent treatment. It evaluates how much hydrostatic pressure the tested specimen resists before water penetration reaches the defined test endpoint.
Water resistance can be influenced by both the inherent characteristics of the fibers and yarns and the complete fabric construction. Coatings, membranes, laminations and finishes can have a major effect on the result.
How Does the Hydrostatic Pressure Test Work?
A fabric specimen is securely clamped in a test head so that water pressure can be applied to one side. The pressure is increased under controlled conditions while the opposite side of the fabric is observed.
The pressure recorded at the specified water-penetration endpoint represents the fabric’s hydrostatic-pressure resistance under the reported test conditions.
The result may be expressed using pressure-related units such as centimetres or millimetres of water column, millibars or kilopascals. The laboratory report should identify both the measured value and its unit.
Buyers should avoid comparing numbers without first checking the units. A large numerical value in one unit may represent the same pressure as a much smaller number in another.
What Does the Result Mean?
A higher hydrostatic-pressure result generally indicates that the tested fabric resisted a greater water pressure before reaching the specified penetration endpoint. However, the number does not provide a universal product classification.
The buyer, brand or finished-product specification must define what result is acceptable for the intended application.
| Report Item | Why Buyers Should Check It |
|---|---|
| Test method and edition | Confirms that the laboratory used the required AATCC TM127 procedure. |
| Result and unit | Allows correct comparison between samples and suppliers. |
| Pressure application condition | Different test conditions can affect the result and comparability. |
| Tested face | Face-to-water orientation may matter for coated, laminated or asymmetric fabrics. |
| Specimen condition | Shows whether the result is initial, washed, aged, abraded or otherwise conditioned. |
| Individual and average results | Helps buyers identify variation that may be hidden by one average value. |
| Specimen observations | May reveal coating damage, edge leakage or unusual penetration behavior. |
Accuracy note: A higher result indicates greater resistance under the specified laboratory conditions. It does not guarantee performance in every rainfall, pressure, wear or finished-product situation.
AATCC TM127 vs AATCC TM22
AATCC TM127 and AATCC TM22 are frequently mentioned together, but they evaluate different water-related properties.
| Comparison Point | AATCC TM127 | AATCC TM22 |
|---|---|---|
| Property measured | Resistance to water penetration under hydrostatic pressure | Resistance of the fabric surface to wetting by a water spray |
| Main buyer question | How much water pressure can the fabric resist before penetration? | Does water bead and roll away instead of wetting the surface? |
| Typical result | A pressure value with a stated unit | A visual spray rating |
| Main performance influence | Fabric density, coating, membrane, lamination and structural integrity | Surface chemistry, DWR treatment, texture and contamination |
| Can it prove surface beading? | No | It evaluates surface wetting behavior |
| Can it measure pressure resistance? | Yes, under the specified laboratory conditions | No |
| Does it prove the finished product is waterproof? | No; seams and the complete product must also be considered | No |
Accuracy note: These methods provide complementary information, but they are not interchangeable. A strong result in one test does not guarantee a strong result in the other.
Can a Fabric Pass AATCC TM22 but Perform Poorly in TM127?
Yes. A fabric can have an effective DWR surface that causes water to bead during a spray test while still allowing water to penetrate its yarn gaps under pressure.
This may occur in lightweight woven fabrics, breathable constructions or materials without a continuous coating or membrane.
Can a Fabric Have High Hydrostatic Pressure but a Lower Spray Rating?
Yes. A coating or membrane may block water penetration even when the outer textile surface begins to wet. This condition is often called surface wetting or wet-out.
Surface wetting can increase water absorption, weight and drying time and may reduce perceived comfort, even if the internal barrier continues to resist penetration.
Do Waterproof Fabrics Need Both Tests?
That depends on the product specification. Rainwear and technical outdoor fabrics may benefit from both surface-repellency and hydrostatic-pressure requirements. Other products may prioritize one property according to the expected exposure.
Factors That Affect AATCC TM127 Results
Fabric Construction
Fabric density, yarn size, weave or knit structure and pore size influence the paths through which water can travel. A tightly constructed fabric may resist pressure better than a more open version, but construction alone does not guarantee a target result.
Coating and Lamination
PU, PVC and other coatings can create a more continuous water barrier. Membrane laminations can also provide water resistance while being designed for moisture-vapor transfer.
Coating thickness, uniformity, adhesion and curing all affect performance. Pinholes, cracks and uneven application can create early leakage points.
Fiber and Yarn Characteristics
Fiber type can influence moisture interaction, but nylon or polyester alone does not establish waterproof performance. Yarn shape, filament construction, texturing and fabric density also affect the finished result.
Stretch
Stretching a fabric can enlarge openings, reduce coating thickness in localized areas or place stress on a membrane. If the material will be extended during use, the buyer should consider whether testing in a representative condition is required.
Dyeing, Printing and Finishing
Dyeing, heat setting, printing, softening and other finishing processes can change the fabric structure or affect coating and lamination quality. Qualification should be based on the final production-representative material.
Laundering, Abrasion and Ageing
Washing, flexing, abrasion, hydrolysis, heat and prolonged storage can reduce water resistance. Initial testing alone may be insufficient for reusable apparel or equipment.
Applications of AATCC TM127 Testing
1. Waterproof Jackets and Rainwear
AATCC TM127 can help buyers evaluate outer-shell, coated and laminated fabrics intended to resist rain penetration.
For apparel development, buyers should also consider:
- Surface water repellency under AATCC TM22.
- Moisture-vapor transmission or breathability.
- Performance after laundering and abrasion.
- Seam-sealing compatibility.
- Garment design, zippers, vents and closures.
- Comfort, weight, noise and hand feel.
A high fabric result cannot compensate for unsealed seams or poorly designed openings in a finished garment.
2. Tents, Shelters and Awnings
Tent and shelter fabrics may experience rain, wind-driven pressure, folding, tension and long-term outdoor exposure. Hydrostatic-pressure testing is useful for comparing coated or laminated constructions during development.
Additional purchasing considerations include:
- Seam leakage and seam-sealing methods.
- Coating adhesion and resistance to flexing.
- Tear and tensile strength.
- UV and weathering durability.
- Flame-performance requirements where applicable.
- Hydrolysis resistance during storage and humid use.
3. Backpacks and Equipment Bags
AATCC TM127 may be used to evaluate the main coated or laminated fabric of backpacks, travel bags, panniers and equipment cases.
However, the complete bag can still leak through needle holes, zippers, bound edges and assembly points. Buyers should decide whether the product needs basic water resistance, protection from short rain exposure or a higher level of finished-product waterproofness.
4. Outdoor Furniture and Equipment Covers
Protective covers for furniture, machinery, vehicles and equipment can use hydrostatic-pressure data to compare fabrics intended to prevent rain penetration.
Outdoor-cover performance also depends on UV stability, coating flexibility, tear strength, colorfastness, ventilation and resistance to standing water. Poor product geometry can allow water to collect and create pressure beyond normal rainfall exposure.
5. Coated and Laminated Technical Fabrics
AATCC TM127 is useful for quality comparison during the development and production of PU-coated, PVC-coated and membrane-laminated fabrics.
Buyers can use the method to investigate:
- Differences between coating formulations.
- Changes in coating weight or thickness.
- Production-lot consistency.
- Damage after flexing, ageing or abrasion.
- Performance before and after laundering.
- Potential pinholes or weak areas in the barrier layer.
How to Specify AATCC TM127 in a Fabric Inquiry
Requesting only “waterproof fabric” or “high water pressure” is not enough for reliable supplier comparison. Include the following information:
- End use: rainwear, tent, bag, cover or another product.
- Target market: country, brand and applicable product requirement.
- Fabric construction: fiber, yarn, weave or knit, weight and width.
- Barrier system: coating, lamination, membrane type or uncoated construction.
- Test reference: full AATCC TM127 designation required by the project.
- Required result: target pressure and reporting unit.
- Pressure condition: the required test option or pressure application condition.
- Water-facing side: face, back or another specified orientation.
- Specimen condition: initial, washed, abraded, aged or flexed.
- Reporting: individual readings, average, units and observations.
- Additional requirement: AATCC TM22 where surface repellency is also needed.
- Finished-product checks: seams, zippers and assembly-level leakage.
Common Buyer Mistakes
- Confusing hydrostatic-pressure resistance with surface water repellency.
- Accepting a result without checking its unit.
- Comparing reports produced under different pressure conditions.
- Failing to specify which fabric face contacts the water.
- Using an initial result when post-laundering durability is required.
- Approving bulk production from a laboratory sample with a different coating or color.
- Assuming every specimen performs consistently because the average result is high.
- Treating a fabric test as proof that all seams and finished products are waterproof.
- Assuming nylon or polyester is waterproof without testing the finished construction.
Frequently Asked Questions
What does AATCC TM127 test?
It measures a textile fabric’s resistance to water penetration under hydrostatic pressure. The result is reported as a pressure value under defined laboratory conditions.
Is AATCC TM127 a waterproof certification?
No. It is a test method. The buyer or applicable product specification must define the required result and any finished-product requirements.
What is the difference between AATCC TM127 and AATCC TM22?
AATCC TM127 measures resistance to water penetration under pressure. AATCC TM22 visually evaluates resistance to surface wetting during a spray test.
Can a fabric have a high TM22 rating but a low TM127 result?
Yes. An effective DWR finish can produce strong water beading while the underlying fabric construction still allows water to pass through under pressure.
Does a high TM127 result guarantee a waterproof jacket?
No. The fabric may resist water pressure, but seams, needle holes, zippers, vents and garment construction can still permit leakage.
Should the fabric be tested after washing?
Yes, when the product is expected to maintain water resistance after care. The washing, drying and conditioning procedures must be defined before testing.
Can results reported in different units be compared?
They may be compared after correct unit conversion, provided the test method and all other important conditions are compatible. Buyers should retain the original values and units on the report.
Final Recommendation
AATCC TM127 provides valuable information about a fabric’s resistance to water penetration under hydrostatic pressure. The result becomes meaningful only when the buyer also defines the units, test conditions, specimen orientation, conditioning and minimum acceptance requirement.
For rainwear and technical outdoor products, combine hydrostatic-pressure data with AATCC TM22 surface-repellency testing when both properties matter. Then evaluate seams, zippers and the completed product according to its real application.
Need Waterproof Fabric for Your Project?
Tell KIGI TEXTILE your end use, fiber, construction, weight, coating or membrane, target hydrostatic-pressure result, required units and durability conditions. Our team can help prepare suitable fabric options and samples for evaluation.
Request Fabric SamplesTechnical reference: AATCC TM127-2017(2018)e, Test Method for Water Resistance: Hydrostatic Pressure. This buyer guide summarizes sourcing considerations and does not reproduce or replace the official standard.
