Waterproof professional terms: hydrostatic pressure, air permeability, water repellency, moisture permeability

I. Hydrostatic pressure (WP):

1. Introduction

Hydrostatic pressure WaterProofness: The outdoor fabric industry is used to call it water resistance, and the unit is mmH2O. It refers to the water pressure strength per unit area. Under standard laboratory conditions, the fabric withstands the pressure of distilled water spraying upwards, and the maximum water pressure is recorded. For example, the water pressure resistance is 5000mmH2O, which means that the unit area can withstand a maximum pressure of 5m without leakage.

2. Common test standards

American standard AATCC 127;

Japanese standard JIS L1092B;

European standard: IS0 811;

3. Test method:

Water pressure resistance test is divided into two methods: before washing and after washing:

Before washing: Domestic outdoor brands generally test the water pressure resistance value before washing, not after washing. The water pressure resistance value drops greatly after washing several times, which may drop by about 1000-3000mmH2O;

After washing: Foreign famous outdoor brands generally test water pressure resistance after 5 washings. THENORTHFACE even uses the method of testing water pressure resistance after 20 washings. Because of the test after multiple washings, the water pressure resistance value drops greatly. Such a test method requires any coating factory or film laminating factory to use better materials for processing. For example, the water pressure resistance of coated fabrics is required to reach 5000mmH2O after 5 washings, so it must be at least 7-8000mmH2O before washing; of course, this requirement will lead to higher prices!

2. Air permeability (MAP):

1. Introduction:

Air permeability (Method Air Permeabbility): refers to the performance of air passing through fabrics; under specified pressure difference conditions, the air flow rate passing vertically through a given area of the sample within a certain period of time is measured to calculate the air permeability. The air flow rate can be measured directly or converted by measuring the pressure of the two sides of the flow aperture.

2. Test standards:

American standard ASTM D737

European standard ISO 9237

Japanese standard JIS L1096;

The air permeability unit can be expressed in mm/s or cm3/cm2/s;

3. Water repellency:

1. Introduction:

In a standard laboratory, distilled water is sprayed on the sample through a funnel and scored and rated against the waterproof standard sample.

2. Test standards:

American standard: AATCC 22;

European standard: ISO 4920;

3. Water repellent is divided into three types:

Ordinary waterproof (Water Repellent, abbreviated as: W/R), durable water repellent (Durable Water Repellent, the outdoor fabric industry is usually called super water repellent, abbreviated as: DWR), Teflon (TEFLON) waterproof;

Ordinary waterproof (W/R): The surface of the clothes will not be waterproof after washing a few times. Generally, ordinary waterproof is enough for outdoor leisure. If you often go mountaineering or mountains with a certain altitude, the weather on the mountain is unpredictable and it may rain at any time. Ordinary waterproof clothing will not be waterproof after washing a few times, causing the surface of the clothes to be wet, and wearing it will increase the weight of the human body.

Super water repellent (DWR): Carbon 6 waterproof produced by Daikin in Japan, after washing 20 times, it maintains an effect of 80 points (European standard level 3); Carbon 8 waterproof used to reach an effect of 80 points after washing 30 times, but it has been banned by the EU because the fluorine content does not meet EU standards.

Teflon (TEFLON), produced by DuPont in the United States, is very well-known. It has three anti-water, anti-fouling and anti-oil effects. The price is relatively expensive. When purchasing this brand of waterproof products, you can provide a Teflon tag, but the disadvantage of Teflon is that the water-repellent effect is not as good as carbon 8 and carbon 6;

4. Moisture Proofness (MP):

1. Introduction:

Moisture Proofness (MP for short), expressed in units of g/m2/24h, refers to the formation of a specific humidity difference on both sides of the sample under certain standard laboratory conditions, and water vapor passes through the sample into the dry side. By measuring the change in the weight of the moisture permeability cup over time, the water vapor permeability and other parameters of the sample can be obtained.

2. Test standards and test methods:

There are two test methods for moisture permeability: positive cup and inverted cup;

Positive cup method: American standard ASTM E96 A, C, E; Japanese standard JIS L1099 A1;

Inverted cup method: American standard ASTM-E96, Japanese standard test JIS L1099B1;

This test uses pre-wash data!

3. The difference between moisture permeability and breathability:

Domestic outdoor practitioners and outdoor enthusiasts call moisture permeability breathable and breathable, or directly call moisture permeability breathable. It is incorrect and imprecise to confuse these two words. Breathable and moisture permeability are completely two concepts, which need to be distinguished and correctly understood; fabrics with three functional indicators of water repellency, moisture permeability and breathability are called waterproof and breathable fabrics, also called windproof, waterproof, warm and breathable fabrics. The simple understanding is that the rain outside cannot come in, and the sweat inside is discharged through the pores of the coating and membrane!