Will Silk Keep Warm When It Gets Wet?

1. Why does silk feel comfortable and a little "warm" when it is dry?
Special structure: Silk is a protein fiber spit out by silkworms. Its structure is like countless small springs with many tiny gaps in the middle. When dry, these gaps can lock some still air. Air, when it is not moving, is a good insulation layer that can slow down the speed at which your body heat escapes. So when dry silk is attached to your skin, you feel it is warm and comfortable. It is not that it is hot, but that it "covers" part of your own heat.

Moisture absorption and heat release trick: Silk has strong hygroscopicity. When you first touch dry silk, it begins to quickly absorb the tiny amount of moisture (sweat) on the surface of your skin. This process of absorbing water vapor will instantly release a little heat, making you feel a short-term, weak warmth at the point of contact. But it does not last long, and the amount is very small, which is different from "keeping warm".

2. Once silk gets wet (literally soaked in water), the situation reverses 180 degrees!

The "air insulation layer" is completely gone: Silk has super water absorption (it can absorb about 30% of its own weight in water without feeling particularly wet). As soon as water comes in, it immediately squeezes out and replaces those precious, heat-insulating static air bubbles in the fiber. Water fills up all the gaps.

Water is a "heat-conducting expert": the thermal conductivity of water is much higher than that of air! Simply put, heat runs dozens of times faster in water than in air! Imagine: dry silk is like a fluffy down jacket (more air), and wet silk is like a soaked cotton T-shirt (more water). The heat in your body is not "locked" now, but is quickly conducted to the cold air outside through the wet silk! It's like you have a "heat sink" attached to your body.

Water evaporates, taking away a huge amount of heat: When wet silk is exposed to the air (even if you are wearing it), the water will continue to evaporate. This evaporation process itself absorbs a lot of heat (evaporation absorbs heat), and this heat is taken away from your skin! This is why you feel very cold when you come out of the swimming pool and the wind blows. Wet silk sticks to your body and continues to evaporate, which is equivalent to continuously "stealing" heat from you, making you feel colder. Silk dries quickly, which is an advantage, but in this evaporation process, it is a "heat pump".

"Cool feeling" becomes "icy feeling": Silk itself conducts heat quickly (slower than wool and down, but faster than cotton and linen), and it conducts heat faster after absorbing water. When wet silk comes into contact with warm skin, it will quickly conduct away the heat of the skin. Coupled with evaporation and heat absorption, the feeling is not "cool", but simply "icy", especially in the windy environment of autumn and winter.