1920s -- Marjorie Joyner's invention helped women of different races. Joyner was born in Virginia in 1896, and began her studies in cosmetology and beauty in 1912. Four years later, she became the first black person to graduate from Chicago's Moler Beauty School, where she met beauty innovator and entrepreneur Madam C. J. Walker.
While overseeing Walker's company in the late 1920s, Joyner invented a wave machine for women's hair. The idea came when she was cooking pot roast one day and noticed the metal rods used to cook and keep the meat together. She translated the heated rods idea into a hair invention that became very popular among both Black and White women.