Waterproof and Breathable Fabrics :

Waterproof and Breathable Fabrics allow vapor to pass through but not liquid. Thus perspiration vapor readily departs from the skin, while water outside the garment cannot enter. The inside of the garment remains free of moisture droplet and helps the body stays warm and dry.

Breathable means the vapor emitted from the surface of an exercising body can evaporate outside the textile, so the temperature decreases and the wearer maintains ultimate comfortableness and dryness. Liquid-water Impermeability means the textile resists water penetration. Most commonly, the surface of this type of textile is coated with PU, PTFE, TPU, TPE or other materials. The same effect can also be achieved by laminating fabric with a water impermeable film.

Hydrophilic materials utilize the hydrophilic group to absorb moisture which then evaporates through diffusion and air convection. Manufactured for specific environmental demands, waterproof & breathable fabrics are available on different combinations of hydrostatic pressure endurance and water-vapor permeability.

Evaluation functionunitTest methodAccording to specifications
water resistance mmH2O Calculate the maximum number of centimeters (mm) of water per square centimeter (mm) area that can withstand without water penetration. The larger the value, the better the water pressure resistance (water resistance). JIS-L1092 / FR(JP)
AATCC-127 / FR(US)
ISO-811 / FR(EU)
Moisture permeability g/m2‧24hrs Calculate the difference between the weight of the vapor-permeable cup before the test and the weight after 24 hours after the moisture-permeable cup is placed under the set conditions, and calculate the moisture permeability. The larger the value, the better the moisture permeability. JIS-L1099 / FR(JP)
ASTM E-96 / FR(US)
Ret m2/Pa‧W Calculation of the water vapor barrier, the smaller the value representative of the penetration of moisture resistance smaller fabric material, have a relatively good moisture permeability more. ISO-11092 / FR(EU)
Water splash Rate 1~5 Splash water beading on treated surface of the garment and rolled, so that the table cloth will not absorb moisture and become heavier, and more preferably breathable. Tested according to a certain temperature, washed a number of times determined splash durability grade, grade 5 is the best. JIS-L1092 / (JP)
ISO4920 / (EU)

With current technology in Taiwan, waterproof & breathable fabrics made by lamination can possess a hydrostatic pressure endurance of at least 40,000mmH2O (ISO 811), a breathability of at least 20,000 g/m2‧24hr (JIS L1099-B1) and a RET of 6 m2pa/w or less. Their counterparts made by direct coating can possess a hydrostatic pressure endurance of at least 10,000mmH2O (ISO 811) and a breathability of at least 10,000 g/m2‧24hr (JIS L1099-B1).

Water vapor resistance, Ret :

Ret Water vapor resistance, Ret (m2.Pa/W)GradeClassification
Ret<6 5 Excellent
6≦Ret<13 4 Very good
13≦Ret<27 3 Good
27≦Ret<40 2 Moderate
40≦Ret<50 1 Fair

Water resistance :

Hydrostatic Pressure(mmH2O)GradeClassification
15000≦Hydrostatic Pressure 5 Excellent
8000≦Hydrostatic Pressure 4 Very good
4000≦Hydrostatic Pressure 3 Good
2000≦Hydrostatic Pressure 2 Moderate
300≦Hydrostatic Pressure 1 Fair

General requirement for pretreatment - Choose the proper general requirement according to product end-use

ItemRequirementTest method
Washing durability Evaluate the appearance after wash first. No damaged appeared, determine the hydrostatic pressure. Cycles of washing decided by the type of textile ISO 6330
Flexing resistance Evaluating the appearance after 2000 cycles flexing ISO 7854
Adhesion strength 200 g/cm up ISO 2411

Edited : ACOTEX Fabric Talks
Info source : Taiwan Functional TextilesIntroduction
From : What are Waterproof and Breathable Fabrics?