People choose polyester/polyamide/4-way stretch/rPET fabrics for their swim shorts. And polyamide is popular for swim trunks in solid color.
What is polyamide?
Polyamide fabric is a general term that is used to refer to a variety of different fabrics that are made from strings of polyamide monomers. The most famous form of polyamide fabric is nylon, but there are quite a few different varieties of this textile.
While these types of fabrics are derived from carbon-based molecules, they are entirely synthetic, which means that they are inherently different from semi-synthetic fabrics, such as rayon, and fully organic fabrics like cotton. Nylon was originally developed by the DuPont Corporation in the mid-1930s as an alternative to silk stockings.
This polyamide was unveiled at the 1939 World's Fair in New York, and the original marketing material for this fabric insisted that it was stronger than steel and entirely resistant to runs. Therefore, DuPont initially intended to market this new synthetic fabric as "no-run," but as it became readily apparent that nylon stockings were, in fact, highly susceptible to runs, the name was changed to "nuron" and later "nilon." Before this fabric entered into mass production, the "i" in "nilon" was replaced with a "y" so that customers would be able to accurately pronounce the name of this fabric.