Why do water Repellent fabrics wear wet?

Fabrics such as Water Repellent and waterproof are two different things

The "water repellent" of the fabric does not mean "waterproof"

Many people have a misconception that the water Repellent function of fabrics means water repellent. Only when they are worn under water for a long time will they penetrate, so they are not really waterproof.  Professor: Actually, water Repellent and waterproof are two different things. Let's explain the differences between them briefly.

Water repellent

Water Repellent, or W/R for short.

Water Repellent means that water repellent is deposited on the surface of the fabric with hydrophobic compounds that will leave pores on the fabric surface, through which air and water vapour can penetrate, and usually form water droplets on the fabric surface (like lotus leaves). This will not be water-repellent, but will reduce the adsorption of water on the fabric so that the water can be "parted" on the fabric surface.  Water will still seep in if it stays there for a long time.

For water-Repellent processing, ultrafine "needle beds" of various chemicals are attached to the surface of cloth so that the surface tension of the cloth is less than the cohesion of water, so that when water drops fall behind, water droplets will roll away rather than spread out and soak.

If this "needle bed" structure is flattened or soaked in oil, the water Repellent ability of the fabric will be greatly reduced and even begin to absorb water.  The water Repellent effects of fabrics will also wear off or even lose their wear due to washing and prolonged use.

So when you wear water Repellent clothes outside on a rainy day, you can quickly peel off the surface moisture, but whether clothes inside will get wet depends on the amount of rain and how long they stay in the rain. Water Repellent is not really completely waterproof.

Waterproof

The English word for waterproof is "water proof", which refers to waterproof and moisture permeable fabric. Generally, it refers to coating and lamination made on the bottom surface of fabric.

Coating is commonly referred to as a coating, lamination refers to the compound of a waterproof material.  The vast majority of waterproof fabrics are laminated (film) materials, but also capsule fiber, compact fabric, silicification and other forms of treatment, and usually located in the inner layer of the fabric, that is, people often say "waterproof film".

Waterproof membrane by pasting process with other material fabric composite film of a composite fabric, the fabric is not waterproof, so when we meet the wet weather in waterproof clothing, will see the water seep into the clothes inside, just like ordinary fabrics of clothing, but the lining of the garment is dry, it is in the middle of the composite fabric waterproof film play a role.

Waterproof ability with water pressure resistance value to express, that is, with a fixed area of waterproof cloth to stop the rising water pressure, when the surface oozing third drop of water is the water pressure resistance value of the fabric, usually more than 1000mmH₂O can achieve the most basic waterproof ability.

The functional distinction between the two

1. Waterproof products will wear water repellent longer than water Repellent products, and their physical and chemical properties will be more stable.

2. Waterproof products usually do not fail due to washing and prolonged use.

3. Waterproof products have higher water pressure resistance indicators than Water Repellent products, usually at least above 3000mmH₂O.

4. In the specific application of clothing, the main role of Water Repellent treatment is to reduce the absorption of water on fabrics so that the water can be "pushed away" on the surface of fabrics;  Waterproofing is a completely impermeable barrier that keeps water out, whether or not the fabric absorbs water.

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