Early hair straightening systems relied on harsh chemicals that tended to damage the hair. In the 1870s, the French hairdresser Marcel Grateau introduced heated metal hair care implements such as hot combs to straighten hair. Madame C.J. Walker used combs with wider teeth and popularized their use together with her system of chemical scalp preparation and straightening lotions. Her mentor Annie Malone is sometimes said to have patented the hot comb. Heated metal implements slide more easily through the hair, reducing damage and dryness. Women in the 1960s sometimes used clothing irons to straighten their hair.