How is hair elasticity evaluated during a strand test?

• A. Gently stretch a strand and observe its ability to return to its original length without excessive elongation or snapping.
• B. Pull the strand hard to test if it breaks instantly.
• C. Soak the strand in water and measure swelling.
• D. Apply heat and observe permanent elongation.

Answer: (A)

Elasticity is measured by how well hair returns to its original length after being stretched. In a strand test, you gently stretch a single strand and watch whether it springs back to its normal length without staying elongated or snapping. This approach reveals the hair’s ability to recover after bending and stretching, which is what elasticity is all about. It’s a safe, practical way to gauge how the hair will respond to chemical treatments or styling that involve stretching or tension. The other methods don’t test rebound: pulling hard to see if it breaks focuses on strength and can cause damage; soaking in water looks at swelling and porosity rather than elastic recovery; applying heat observes deformation under heat, which is more about heat resistance than recoil after a small stretch.