When reading a book today I came across something I've never heard about before. It describes a type of lifevest used very early the war (1939), which had a kind of a powder in a bag in the front and back of the vest. This powder, when it got wet, would keep a man afloat in the water for 16 hrs. It looked like an ordinary vest, and I understand it was just like any other piece of clothing which the sailors could easily wear 24 hours a day underneath their shirt or sweater while working or even sleeping.

Does anyone have any more details on this type of vest - was it used during the war only? Did it have a name? What kind of powder was it? Do we have anything similar today?

Siri