Helanca was a popular elaticized yarn that is made of nylon and polyester, is somewhat slow at water absorbsion and was used quite readily in swimwear beginning in the 1950s. It hugs the body and enhances all the curves. Helanca was also used extensively in lingerie, including corsets and girdles. Even ski pants and snow trousers used the fiber to much success. In fact, Helanca is still being used today.
This is a Jantzen suit from the International set that is also made of Helanca. The fabric has two way stretch and is very sturdy. I've always loved these suits. If youever find one, don't hesitate to pick it up. it will last you a life time.