A mysterious woman jumped into a river recently, but she was rescued because of the buoyancy provided by her down jacket. She remained afloat for over 20 minutes before being pulled to safety. How could a simple jacket offer such life-saving support? According to experts, the unique properties of down jackets make them surprisingly effective in water.
**News Recap**
On January 10th, Ms. Li, a citizen from Yanshi, was out with friends at a KTV. After an emotional night, she left the venue around 2 a.m. on the 11th and decided to take a walk near a bridge over a river. While her friends weren’t paying attention, she suddenly jumped into the water.
Emergency services were quickly called, and after more than 20 minutes of effort, Ms. Li was rescued by a river management boat. Medical staff confirmed that she was not seriously injured. “She was wearing a down jacket, which helped her stay afloat and prevented a tragic outcome,†police said.
**Understanding the Buoyancy of Down Jackets**
So why do down jackets float? There are two main reasons:
1. **Water-Resistant Fabric**
Most down jackets are made from synthetic materials that have a "water-repellent" property. Unlike cotton or linen, which absorb water easily, these fabrics resist moisture. This means that when a down jacket gets wet, it doesn’t soak through immediately, keeping the down inside dry for a longer period.
Professor Yin Shumei from Qingdao University of Science and Technology explained that this water resistance is a key factor. “It’s a material science concept known as hydrophobicity — the ability to repel water.†This feature helps maintain the air pockets within the down, which contribute to buoyancy.
2. **Down Volume and Air Expansion**
The second reason lies in the down itself. When dry, down feathers are light and fluffy, creating a lot of air space. When submerged in water, the down begins to absorb some moisture, but the air trapped inside still provides lift. The volume of the down increases slightly, making the jacket less dense than water, allowing it to float.
This is similar to what happens in a washing machine: a down jacket tends to float due to the air trapped in the feathers. However, if all the air is squeezed out, the jacket will sink.
**Are All Down Jackets Buoyant?**
Not necessarily. It depends on the materials used. Some down jackets are made with cotton or other fabrics that don’t have water-repellent properties. These may not provide any floating effect in water. Additionally, the waterproofing of the fabric can vary depending on the brand and construction.
Even if a jacket is waterproof, prolonged exposure to water will eventually cause the down to become saturated, reducing its buoyancy. So while a down jacket can be a lifesaver in an emergency, it's not a substitute for a proper life jacket.
In conclusion, the combination of water-resistant fabric and the natural buoyancy of down makes certain types of down jackets effective in helping people stay afloat in water — just like in the case of Ms. Li, who was lucky enough to survive thanks to her jacket.
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