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Start by defining the water exposure your design must withstand: surface droplets, rain, impact splash, or sustained water pressure. Then select a material construction and a test method that represent that exposure. “Water repellent” describes surface behavior; hydrostatic waterproofness is resistance to water forced through a material under pressure. These claims are not interchangeable.
Define what “wet-proof” must mean for the product
There is no single test result that proves a material is suitable for every wet environment. A fabric exposed to brief splashes faces a different failure mode from one expected to resist rain or sustained pressure. Write the requirement around the actual use before comparing materials or supplier claims.
- Surface wetting: Does water bead or spread across the face of the material?
- Rain: Must the material resist water falling on it over a specified period?
- Impact penetration: Could splashes or droplets strike with enough force to pass through?
- Hydrostatic pressure: Must the material resist water pushed through it under pressure?
Also define duration, temperature, movement, and whether seams, closures, or joints are part of the requirement. These are application-specific design choices; the standards described below do not establish universal thresholds for them.
Choose a test that measures the failure mode
A test name matters because different methods measure different properties. A spray-repellency result does not establish resistance to water forced through fabric under pressure, and a fabric test does not by itself establish that a finished product is waterproof.
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| Method | What it addresses | Useful distinction |
|---|---|---|
| AATCC TM22 | Spray repellency | Addresses surface response to spray, not hydrostatic pressure. AATCC method catalog |
| AATCC TM35 | Rain resistance | A rain method, distinct from spray and hydrostatic methods. AATCC method catalog |
| AATCC TM42 | Impact penetration | Addresses water penetration from impact. AATCC method catalog |
| AATCC TM127 | Hydrostatic pressure resistance | Measures resistance to water penetration under hydrostatic pressure; results may differ from rain or spray methods. AATCC method summary |
| AATCC TM204 | Water-vapor transmission | Addresses vapor transmission, a separate property from liquid-water resistance. AATCC method catalog |
| AATCC TM79 | Absorbency | Measures a different property from resistance to penetration. AATCC method catalog |
AATCC describes TM127 as a method for measuring resistance to water penetration under hydrostatic pressure. It applies across fabric types, including treated fabrics. AATCC also cautions that results may differ from rain and spray methods; if a restraint is required, its TM127 summary points to TM208. Read the TM127 summary.
Specify the material construction and evidence
For rubber- or plastic-coated fabric
ASTM D3393-91(2022) sets minimum hydrostatic-resistance requirements for rubber- or plastic-coated fabrics. The ASTM page identifies this as the active edition and gives its last update as November 7, 2022. Materials that meet the specification are considered waterproof under it; the specification explicitly does not cover water repellency or water resistance. See ASTM D3393-91(2022).
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The coating category alone is not proof that a particular fabric meets your design need. Ask for a verified result against the relevant requirement, and identify the material construction and test edition with that result.
For other textile fabrics
Do not assume a coated-fabric specification applies to a different construction. Select an applicable method for the textile and exposure, then request supplier evidence for that method. AATCC notes that hydrostatic resistance depends on fiber and yarn repellency as well as fabric construction, so a surface treatment or fiber description alone cannot establish the result. CDC PPE-Info: AATCC 127 standard details.
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- BREATHABLE AND DOESN’T FADE: Odorless water repellent spray does not impede fabric breathability and will also not cause your clothes to fade, so you can enjoy Summer get-togethers
For rainwear fabrics
ASTM D7017-20 covers rainwear and all-purpose water-repellent coat outer fabrics made from textile fibers or blends. It is an apparel-specific performance specification, not a universal standard for products exposed to water. See ASTM D7017-20.
Validate the complete design, not only the fabric
- Document the exposure. Describe whether the product faces droplets, rain, impact, or pressure, along with duration, temperature, and movement.
- Set a quantitative requirement. Define what level of performance is needed for that use rather than relying on labels such as “wet-proof” or “waterproof.”
- Choose the relevant construction and method. Match the material type and failure mode to a named standard or test method, and record its edition.
- Request supplier results. Ask for the tested specimen construction and result. Do not infer hydrostatic performance from a spray rating or marketing description.
- Check the assembly. If product performance depends on seams, closures, or joints, evaluate those features as part of the finished design. Fabric methods alone do not prove whole-product waterproofness.
- Set durability exposures. Reassess after relevant wear, flexing, cleaning, or aging. Establish conditions that represent the intended product; the cited method summaries do not prescribe a universal durability schedule.
Treat breathability and liquid-water resistance separately
If moisture-vapor transmission matters, state it as a separate design requirement and choose a method that measures it. AATCC lists TM204 for water-vapor transmission; a result for liquid-water resistance does not establish vapor performance, or vice versa. AATCC method catalog.
Quick Recap
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- WATER REPELLENT SPRAY: One Scotchgard Outdoor Water Shield Spray, 13 oz can, that protects fabrics against the elements
- IDEAL FOR MANY OUTDOOR ITEMS: Water repellent spray is ideal for use on outdoor fabrics during the rainy Spring season, including tents, outerwear, rain gear, umbrellas, patio furniture, outdoor gear, backpacks, canvas tarps, boat covers and more
- SAFE FOR MANY FABRICS: Use this fabric spray before Spring and Summer outings on polyester, nylon, polypropylene, cotton, leather, suede and more
- BREATHABLE: Water repellent spray does not impede fabric breathability, so you can enjoy rainy camping trips during the Spring season
- ODORLESS: Stain sprayer dries clean and odorless, so you don't have to worry about ruining outdoor gear
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