5mm, 3mm, 2mm, 1mm, etc. are used as the fabric for wetsuits, but depending on the style of the wetsuit (full suit, vest, etc.), surfing place, season, etc. The thickness of the fabric changes. In the zero wetsuit, the winter wetsuit usually uses 3.5mm thick rubber, but it is annoying, so the decimal point is cut off and displayed as 3mm. Originally, the thickness of rubber is not accurate because it expands and contracts. The manufacturer also says that 0.5mm is within the margin of error.

A long time ago, I went to visit a factory that manufactures rubber, but when I look at the manufacturing process, I see a sponge that is 2 cm to 5 cm, 15 cm, and now thicker, about 20 to 30 cm thick. (Neoprene rubber) was baked on a large square frying pan. Then slice the baked sponge. It's commonly called half-cutting, but I divide the rubber in half and half. There is a machine with rollers on both sides and a knife in the middle, sandwiching the rubber, passing through it, and halving. After all, considering the cost, it is troublesome to bake many times, so there is a tendency to bake thickly. Neoprene rubber is a closed cell, so even if sliced, the bubble will not penetrate the rubber fabric body. When sliced, there are small holes and bumps, but there is no problem because the surface is coated with adhesive and the jersey is stretched over it. Because the glue is a film. However, many people say that if you use a skin type that does not have a jersey attached, and if it is made of soft rubber, you will scratch the surface with claws or fins and damage it, so I don't like it. Only here, O'Neill used to use a fabric called Lavatex, which was a very rational and durable rubber. But the price was so high that Jack O'Neill came to Japan in search of cheap rubber. So Sed Science started selling it with a press afterwards like Lavatex, and then exported it to the United States, and O'Neill also started using the rubber. As I wrote before, the first company also used Sed Science rubber. (to be continued)