About 10 years ago, I brought it to a university to study the heat retention of rubber. As a result of bringing in various materials for about three years and examining them, it was found that the thicker the rubber of the sponge, the warmer it is. The thicker it is, the warmer it is. As a result of comparing and researching various materials such as brushed type, extended jersey type, far infrared rays, and titanium film as the inner material, the difference in heat retention effect between the materials was only 0.1% or less. The only effect and difference was that it was soft to the touch. However, it's true that it's warmer if you let the air in your wetsuit. It's the same with clothes, and it's important that the warmth is different depending on how much air can be stored in the wetsuit. Materials that cannot store air inside, such as titanium film, were not very effective no matter how much they were applied. Even if it is a far-infrared material, it may be good if it contains air. In the end, I came to the conclusion that the thicker the rubber, the warmer it is.

In other words, it's rubber-thick equal heat retention. If you want to enter the cold sea, you can use thick rubber. In Japan, 5mm is enough. A few years ago, there was a wetsuit maker who released a thin wetsuit with the catch that "If you have a 2mm thick wetsuit, you can use it all year round", but even in Shonan, I was delighted with the 2mm wetsuit at the surf shop. I was selling it. But as expected, I can't use it all year long, let alone winter. It's decided that it's cold to enter the cold sea with such a 2mm thick wet suit. Well, in January and February, if water doesn't come in, it may be okay for about an hour. A warm wetsuit is a thick fabric. It's a matter of course, but if you make the fabric thicker, it will naturally become difficult to move. The wetsuit maker called Zero is thinking about how to solve the problem of getting stuck. (to be continued)