Detecting method and apparatus for permanent wave hairdressing

摘要

A method for detecting a condition of permanent waves during a permanent wave hairdressing, by using a chemical liquid which makes permanent waves and which produces a hydrogen sulfide gas at a predetermined temperature, and by exposing a lead acetate test paper to the hydrogen sulfide gas which changes colors to indicate the condition of the permanent wave. An apparatus having a light emitting diode detects the change in color of the test paper and activates a buzzer when a predetermined change of color is detected.