What length of hair was Charles Nessler's heat permanent waving machine suitable for?

• A. Short
• B. Medium
• C. Long
• D. Very Long

Answer: (C)

This question hinges on how Nessler's heat permanent waving machine actually worked. The device set curls by wrapping sections of hair around heated rods and exposing them to heat. That wrapping and even heating require enough hair length to grip and hold the curl reliably. Short hair can’t be wrapped securely, so it wouldn’t form a lasting wave with this method. Very long hair would still work, but long hair hits the practical balance where there’s enough length to wrap into multiple sections and achieve consistent results. So, the machine was suitable for long hair.