Many GORE-TEX products are treated with an ultra-thin durable water repellent (DWR), a polymer that’s applied to the outermost fabric layer. DWR reduces the surface tension of the fabric, so that water simply rolls off.
If the DWR on the textile is fully functional, water droplets from rain gather on the surface of the DWR coating as round drops and roll off if the textile surface is held at an angle.
However, if the DWR on the textile is worn off, water droplets can penetrate into the textile.
Regular wear and tear, exposure to sunscreen lotion, dirt, detergents, insect repellent, other materials can shorten the lifespan of the treatment. If that happens water can saturate the outer fabric of your gear making you feel damp and clammy, as if your gear was leaking.
The good news: restoring the water repellency of your GORE-TEX product is extremely easy.