In 1926, she started looking for an easier way for African American women to straighten their hair. She took her inspiration from a pot roast cooking with rods inserted to speed the process. Joyner experimented initially with pot roast rods and soon invented a Permanent Wave machine that could be used to curl or straighten hair by wrapping it on rods above the person's head and then cooking them to set the hair. This method also allowed hairstyles to last several days, whereas previously they became unkempt at the end of one. She patented it in 1928, (U.S. pat. #1,693,515) becoming the first African American woman to receive a patent.
Joyner's machine was popular in salons with both African American and white women. The patent was credited to Madame Walker's company and she received almost no money for it. In 1945, she cofounded the United Beauty School Owners and Teachers Association. In 1973, at the age of 77, she was awarded a bachelor's degree in psychology from Bethune-Cookman College in Daytona Beach, Florida.
Currently, her papers reside in the Vivian G. Harsh Research Collection of Afro-American History and Literature at the Chicago Public Library.
"If I can take pot roast rods and have a one-of-a-kind invention, believe me, people can do what they set their minds to."