Water vapour permeability test and water vapour absorption test are essential for evaluating the performance of materials in various applications. The ISO 17699 and EN ISO 20344 standards provide guidelines for these tests, Ensuring that materials meet the required specifications for moisture management. With the help of advanced testing equipment such as water vapour permeability testers, water vapour absorption testers, and water vapor transmission test equipment, Manufacturers can ensure that their products perform well in real-world conditions. These tests not only enhance material performance but also improve user comfort and product durability, Making them a crucial part of the material evaluation process.

Understanding the interaction between materials and moisture is crucial for many industries, Especially in the manufacturing of textiles and footwear. This is where the Water Vapour Permeability (WVP) Test and Water Vapour Absorption (WVA) Test come into play. These tests are essential for assessing the suitability of materials for their intended use. This article will delve into these tests, focusing on the ISO 17699 standard, the EN ISO 20344 standard, and the related equipment used in these evaluations. By understanding and implementing these tests, Industries can better manage moisture and ensure that their products meet the highest standards of quality and performance.

Water Vapour Permeability (WVP) is a measure of how well a material allows water vapor to pass through it. This is a critical property for materials used in clothing, footwear, and various other applications where moisture management is essential. The WVP test evaluates how effectively a material can handle the passage of water vapor, Which can impact comfort, durability, and overall performance.	Water Vapour Permeability (WVP)
Water Vapour Absorption (WVA) refers to the ability of a material to absorb water vapor. This property is particularly important for materials used in environments where moisture exposure is frequent. The WVA test helps in understanding how much moisture a material can hold, Which can affect its performance, longevity, and user comfort.	Water Vapour Absorption (WVA)

5.1.1 Unless otherwise specified, cut three samples of dimensions 70 mm x 45 mm.	5.1 Water Vapour Permeability Test Method	5 Sampling and Conditioning ISO 17699 EN 13515
5.1.2 For sheet materials cut test specimens from a range of positions across the full usable width and length of the sheet material. For a material with a woven structure this should prevent any two specimens containing the same warp or weft threads. Prepare test pieces from complete upper assemblies when the lining material is permanently attached to the upper material
5.1.3 For test specimens cut from footwear uppers avoid any areas containing seams or perforations and any other desian features which mean that the test specimen will not be of uniform thickness across its entire surface area.
Note: It may not be possible to cut a test specimen of sufficient size from certain types of footwear, especially children’s and the test specimen size should not be reduced. lf it is not possible to cut the correct size test specimen from a shoe upper the materials themselves must be tested.
5.1.4 Mark each test specimen with a unique reference code.
5.1.5 Store the cut test specimens in a standard controlled environment specified in EN 12222 for at least 24 h prior to testing and carry out the test in this atmosphere.
5.1.6 Carry out 20 000 cycles according to EN 13512
5.2.1 lf the test is being carried out to assess a single material, then cut two circular test specimens with a diameter of 45 mm ±5 mm.	5.2 Water Vapour Absorption Test Method
For sheet materials, cut test specimens from a range of positions across the full usable width and length of the sheet material. For a material with a woven structure this should prevent any two specimens containing the same warp or weft threads.
5.2.2 lf the test is being carried out to assess a composite assembly of materials used in a complete product such as a lined shoe, then cut two circular test specimens, with a diameter as specified in 5.2.1, from each of the materials used in this assembly.
5.2.3 For test specimens cut from footwear uppers avoid any areas containing seams or perforations and any other design features which mean that the test specimen will not be of uniform thickness across its entire surface area.
Note: It may not be possible to cut a test specimen of suficient size from certain types of footwear, especially children’s and the test specimen size should not be reduced. lf it is not possible to cut the correct size test specimen from a shoe upper the materials themselves must be tested.
5.2.4 Mark each test specimen with a reference number
5.2.5 Store the test specimens in a standard conditioned environment as specified in EN 12222 for at least 24 h before starting the test.
5.2.6 Carry out 20 000 cycles according to EN 13512.

Equipment Model	WEW-WVP-WVA-001	WEW-WVP-WVA-002
Internal Dimension(W*D*H)	400×500×500mm（100L）	500×500×600mm（150L）
External Dimension(W*D*H)	900×1075×1400mm	700×1170×1510mm
Internal Material	1.2mm Thickness SUS#304	Stainless Steel, Mirror Finished
External Material	1.2mm Thickness	Cold-rolled Steel Plate Baking
Temperature Range	-40℃ ~ + 150℃	-60℃ ~ + 150℃
Temperature Fluctuation	±0.5 ℃	±0.5 ℃
Temperature Uniformity	≤2℃	≤2℃
Temperature Rate 1	1℃ – 1.5℃/min	1℃ – 1.5℃/min
Temperature Rate 2	3℃ – 3.5℃/min	2.5℃ – 3.5℃/min
Humidity Range	20%~98%RH	20%~98%RH
Humidity Fluctuation	±3% RH	±3% RH
Power Voltage	AC 220V ±10%, 50Hz, 60Hz	AC 220V ±10%, 50Hz, 60Hz
Humidity Uniformity	±2% RH	±2% RH
Working Positions	6 Positions	6 Positions
Fan Dimension	90x75mm(LxW)	90x75mm(LxW)
The Blade Angel	120 Degrees	120 Degrees
Fan Speed RPM	(1400±100) rpm.	(1400±100) rpm.
Water Vapor WVP
Working Positions	6 Postions	6 Postions
Testing Piece	Diameter φ4.3cm	Diameter φ4.3cm
Inner test Bottle	3.5 cm	3.5 cm
Metal Container Holds	50 ml	50 ml
WVA Fixture Size	340*210*130mm	340*210*130mm
Water Absorption

A circular test specimen is clamped across the open end of a test pot containing a moisture absorbing desiccant.Air of specified humidity and temperature is blown over the test specimen at a set velocity. The alr within the pot is circulated by moving the pot which acitates the desiccant. After a measured time the mass of water vapoul transmited through the test specimen is determined and the water vapour permeability of the material calculated.	6.1.1 Principle	6.1 Water Vapour Permeability Test Method	6 Test Method ISO 17699 EN 13515
6.1.2.1 Pour freshly dried silica gel (see 4.1.4) into one of the pots (see 4.1.1) until it is half full	6.1.2 Procedure
6.1.2.2 Place a test specimen centrally over the open end of the pot prepared in 6.1.2.1 so that the surface which would be closer to the source of water vapour in the final product is uppermost. For example if assessing the perspiration transmission properties of a footwear upper material, then the surface which willbe nearer to the foot should be uppermost.
6.1.2.3 Fit a clamping ring (see 4.1.1.2) centrally over the top of the test specimen and tighten the ring so that the test specimen is securely held around its edges and the pot is sealed.
6.1.2.4 Repeat the procedure in 6.1.2.1 to 6.1.2.3 for the remaining two test specimens.
6.1.2.5 Place each filed test pot onto the turntable (see 4.1.2.1) and operate the test machine for 20 h ±4 h. This is to condition the test specimens.
6.1.2.6 Remove each of the test pots from the turntable.
6.1.2.7 For each test pot and as quickly as possible remove the clamping ring to release the test specimen pour away the silica gel from inside the pot, refill the pot with a similar amount of freshly dried silica gel and replace the test specimen and clamping ring on the pot by repeating the procedure in 6.1.2.2 and 6.1.2.3
6.1.2.8 With the minimum of delay use the balance (see 4.1.3) to measure the combined mass of each test pot, silica gel and test specimen assembly, and record these values as M, to the nearest 1 mg. Record the time that these measurements were made as 7o
6.1.2.9 Replace the test pots on the turntable and start the machine.
6.1.2.10 After 11,5 h ±4,5 h stop the test machine and remove the test pots from the turntable
6.1.2.11 With the minimum of delay use the balance to measure the combined mass of each of test pot, silica gel and test specimen assembly, and record these values as M, to the nearest 1 mg. Also record the time that these measurements were made as T1.
Either a single circular test specimen or an assembly of circular test specimens which is representative of a completed product or taken from a closed shoe upper, is clamped between an impermeable membrane and the open end of a vertical cylindrical chamber containing a specified volume of water. After a set time the mass of water absorbed by the test specimen is measured.	6.2.1 Principle	6.2 Water Vapour Absorption Test Method
6.2.2.1 Use the balance (see 4.2.2) to measure the mass of each test specimen and record these values as M0, to the nearest 1 mg.	6.2.2 Procedure
6.2.2.2 lf assessing an assembly of materials prepare two test specimen stacks as follows: Place one test specimen of each type of material that is to be tested together, centrally on top of each other so that the order and orientation of the specimens in the stack are the same as in the final oroduct, f possible ioin toaether the test specimens in each stack using a similar method to that used in manufacture of the actual product. for example by bonding together with an adhesive layer. The stacks will subsequently be referred to as test assemblies.
6.2.2.3 Pour 50 cm3 ±5 cm3 of distilled water, temperature according to EN 12222, into each of the two pots.
6.2.2.4 Place a test specimen or test assembly centrally over the top of each clamping ring so that the surface which will be inside the footwear is lowermost.
6.2.2.5 From this stage onwards take great care to keep the pots vertical and avoid rapid or jerky movement which might splash water onto the test specimen.
6.2.2.6 Place a piece of impermeable material (see 4.2.5) centrally over the top of each test specimen or test assembly.
6.2.2.7 Place a disk (see 4.2.1.2) centrally over the top of each piece of impermeable material and clamp the disks to the pots so that the test specimens are securely held around their edaes and the pot is sealed.
6.2.2.8 Place the pots in an environment of temperature of according to EN 12222 for 8,0 h ±0,1 h.
6.2.2.9 Quickly dismantle the two test pots taking great care not to splash any of the water onto the test specimens and use the balance to measure the mass of each of the test specimens. Record these values as Mf to the nearest 1 mg.

The ISO 17699 standard specifies two test methods to assess the water vapour permeability and water vapour absorption of materials, specifically uppers or complete upper assemblies, regardless of the material type. This standard is crucial for evaluating the suitability of materials in their final applications. The tests are conducted under controlled conditions to ensure accurate and consistent results. The EN ISO 20344 standard, on the other hand, focuses on the testing of personal protective footwear. It includes procedures for evaluating various properties of footwear, including water vapour permeability and absorption. This standard ensures that the footwear provides adequate protection and comfort under different conditions.

4.1.1 The following apparatus and material shall be used: Cylindrical test pots each with an internal height of 80 mm ±10 mm and internal volume of 100 cm3 ±20c3, and including the following:	4.1 Water Vapour Permeability Test Method	4 Apparatus and Material ISO 17699 EN 13515
4.1.1.1 One circular open end with an internal diameter of D= 30 mm ±1 mm and is known to the nearest 0,1 mm.
4.1.1.2 A clamping ring with an internal diameter D.
4.1.1.3 Means of tightly clamping a test specimen between the clamping ring and the open end so that the pot is sealed by the test specimen.
4.1.2 Test machine (see Figure 1)including the following:
4.1.2.1 Vertically mounted turntable which:
a) has at least three test stations, each of which is capable of holding a test pot so that its axis is parallel to, and 67 mm ± 2 mm from the axis of rotation of the turntable;
b) is rotated at 7,8 rad/s ±0,5 rad/s1)
4.1.2.2 Paddle type fan which:
a) has three flat blades inclined at 120° to one another. The blades shall be flat with approximate dimensions 90 mm x75 mm;
b) is mounted so that its axle is coaxially aligned with the axis of the turntable (see 4.1.2.1) and the blades pass within a distance of 10 mm ±5 mm of the open ends of test pots (see 4.1.1) mounted on the turntable;
c) is rotated at 146 rad/s ±10 rad/s in a direction opposite to the direction of rotation of the turntable.
Figure 1 – Schematic diagram of apparatus to be used in the water vapour permeability test
4.1.3 Analytical balance capable of measuring mass up to 200 g to the nearest 1 mg.
4.1.4 Silica gel with a particle size greater than 2 mm and which is preferably self indicating.
Freshly dry the silica gel in a ventilated oven at 125° C ±5 °C for at least 16 h and cool in a sealed container for at least 6 h. Once dried the silica gel will remain dry for many days if kept in air tight containers. Typically the colour of self indicating silica gel will turn from blue when dry to pink or colourless when saturated.
4.1.5 Press knife, or similar cutting device, capable of cutting test specimens with a diameter which is sufficiently larger than D to enable a good seal to be made around the open end (see 4.1.1.1) of the pot.
4.2.1 Two round test pots each with a volume of 100 cm3 ±20 cm3 and including the following.	4.2 Water Vapour Absorption Test Method (see Figure 2)
4.2.1.1 One open end with a flat annular surface of internal diameter of 35,0 mm ±0,5 mm and external diameter of at least 20 mm larger. The external diameter can be provided by a flange of minimum width 10 mm or by a cylinder of minimum wall thickness 10 mm.
4.2.1.2 A metal disk of diameter greater than 55 mm.
4.2.1.3 Means of tightly clamping a test specimen and a piece of impermeable material (see 4.2.5) between the open end and the disk so that the pot is sealed by the test specimen.
4.2.2 Analytical balance capable of measuring mass up to 100 g to the nearest 1 mg.
4.2.3 Device capable of measuring time up to 8 h to the nearest 0,1 h, e.g., a stopwatch.
4.2.4 Distilled or deionised water complying with EN ISO 3696.
4.2.5 Two circular pieces of impermeable material of minimum diameter 55 mm.
4.2.6 Cutting device such as a press knife, capable of cutting test specimens of diameter 45 mm ±5 mm.
Figure 2 – Apparatus for determination of water vapour absorption

Materials used in clothing and footwear need to manage moisture effectively to ensure user comfort and performance. The WVP test helps determine how well a material can breathe and allow moisture to escape, while the WVA test evaluates how much moisture the material can absorb. Both tests are essential for ensuring that the material performs well in real-world conditions.	1. Ensuring Material Performance	The Importance of Water Vapour Permeability and Absorption Testing
Materials that do not manage moisture effectively can deteriorate faster. By conducting WVP and WVA tests, manufacturers can select materials that offer better durability and longer service life. This is particularly important in the footwear industry, where exposure to moisture can lead to premature wear and tear.	2. Enhancing Product Durability
Comfort is a key factor in the success of clothing and footwear. Materials that manage moisture well help keep the wearer dry and comfortable. The WVP test ensures that moisture does not build up inside the material, while the WVA test helps in understanding how much moisture the material can handle before it affects comfort.	3. Improving User Comfort**
In the footwear industry, WVP and WVA tests are used to ensure that materials used in uppers and linings provide adequate moisture management. This helps in improving the comfort and durability of footwear.	1. Footwear Industry**	Applications and Benefits of WVP and WVA Testing
For textiles, these tests are crucial in determining how materials will perform in various environmental conditions. This information helps manufacturers design the products that offer better comfort and longevity.	2. Textile Industry
In protective clothing, The effective moisture management is essential for user safety and comfort. WVP and WVA tests ensure that materials meet the necessary standards for moisture resistance and absorption.	3. Protective Clothing**