Charles Nessler is usually credited with inventing the permanent wave in the early 1900s. And he made a huge fortune from it, while also bolstering a huge beauty industry.

Research:

• Bedi, Joyce. “GERMANY | Charles (Karl) Nessler.” Lemelson Center for the Study of Invention and Innovation. Smithsonian National Museum of American History. June 3, 2021. https://invention.si.edu/node/29205/p/732-germany-charles-karl-nessler
• Hellman, Geoffrey T. “Profiles: Hair Scientist.” The New Yorker. April 29, 1933. https://archives.newyorker.com/newyorker/1933-04-29/flipbook/020/
• Larkin, Theresa. “From straight to curly, thick to thin: Here's how hormones and chemotherapy can change your hair.” MedicalExpress. Jan. 14, 2024. https://medicalxpress.com/news/2024-01-straight-curly-thick-thin-hormones.html
• “115 Years of Long-Lasting Curls: The History and Rebirth of the Perm.” Estetica Magazine. Feb. 8, 2022. https://www.esteticamagazine.com/2022/02/08/111-years-of-long-lasting-curls-the-history-and-rebirth-of-the-perm/
• Marsden, Rhodri. “Rhodri Marsden's Interesting Objects: The Nessler Permanent Wave Machine.” The Independent. Oct. 9, 2015. https://www.independent.co.uk/life-style/fashion/features/rhodri-marsden-s-interesting-objects-the-nessler-permanent-wave-machine-a6674081.html
• “Modern Living: The Great Wave.” Time. Feb. 5, 1951. https://time.com/archive/6825188/modern-living-the-great-wave/
• Morton, Ella. “The Alarming Aesthetics of Jazz Age Perm Machines.” Atlas Obscura. Aug. 2, 2016. https://www.atlasobscura.com/articles/the-alarming-aesthetics-of-jazz-age-perm-machines
• Nessler, Charles. “The Story of Hair.” New York. Bonni and Liveright. 1928.
• Nessler, Charles. “A New or Improved Method of and Means for the Manufacture of Artificial Eyebrows, Eyelashes and the like.” UK Patent Office. Accessed via Google: https://patents.google.com/patent/GB190218723A/en
• “Nessler, Invented Permanent Wave.” New York Times. January 24, 1951. https://timesmachine.nytimes.com/timesmachine/1951/01/24/88426426.pdf?pdf_redirect=true&ip=0
• “A Revolutionst Dies.” Life Magazine. Feb. 5, 1951. Accessed online: https://books.google.com/books?id=50sEAAAAMBAJ&q=nestler#v=onepage&q=nessler&f=false
• Sheen, Maureen. “Story of Us, 1910-1920: Do the Wave.” American Salon. Jan. 20, 2016. https://www.americansalon.com/products/story-us-1910-1920-do-wave