Adora' women's light blue rubber bathing cap. Patterned over the surface flowers in relief. It is shaped to cover the ears and back of the head. Swim caps were made of rubberized fabric during the early 20th century. By the 1920s they were made of latex. The earliest chin strap caps were known as "aviator's style caps" as they resembled the strapped leather helmets of flyers of the day. During the 1940s swim caps became scarce as rubber was needed for war materials. The permanent wave hairstyle took time to obtain and was expensive, so many women wanted to protect their hair while swimming. The 1950s saw decorated caps come into vogue, and during the 1960s colourful flower petal swim caps became popular.