NIC Cosmetology Written (Theory) ExamScientific ConceptsMedium
A cosmetologist is preparing to perform a chemical perm service. Before applying the waving lotion, they must ensure the client's hair has been properly shampooed and rinsed. Which type of chemical bond in the hair is primarily responsible for maintaining the hair's natural curl pattern and is broken and reformed during a perm service?
- AHydrogen bonds
- BDisulfide bonds
- CSalt bonds
- DPeptide bonds
Show answer & explanationAnswer & explanation
Correct answer: B. Disulfide bonds
Disulfide bonds are strong chemical bonds that give hair its strength and shape. Perm services involve breaking and reforming these bonds to create a new curl pattern.
Why the other options are wrong
- A. Hydrogen bonds are weak physical bonds easily broken by water or heat, and reform when dry, contributing to temporary styling.
- C. Salt bonds are weak physical bonds that are also easily broken by changes in pH, contributing to temporary styling.
- D. Peptide bonds link amino acids to form protein chains, but are not directly altered to change hair shape in a perm.
Disulfide Bonds
Strong chemical bonds in the hair that contribute to its strength and elasticity, and are altered during chemical services like perms and relaxers.
- Responsible for hair's natural curl and strength.
- Broken by reducing agents (thioglycolate) in perms.
- Reformed by oxidizing agents (neutralizer) to set new shape.
Memory trick: Disulfide bonds are the 'Durable Designers' of hair shape, broken and rebuilt for perms.