Which side bond is of greatest concern to the salon professional?

• A. Salt bond
• B. Disulfide bond
• C. Hydrogen bond
• D. Van der Waals forces

Answer: (B)

Disulfide bonds are the strongest links in the hair’s cortex, formed between sulfur atoms in cysteine. They’re the bonds chemistry services actually target to permanently change hair shape, because a reducing agent breaks them, the hair is reshaped, and a neutralizer reforms them in the new configuration. That makes them the primary focus for salon professionals when performing perms, relaxers, or other permanent changes. The other side bonds—salt bonds and hydrogen bonds—are more temporary: salt bonds weaken with changes in pH and tend to reform when the pH is restored, while hydrogen bonds break with moisture or heat and re-form as the hair dries. Van der Waals forces are weaker, more physical attractions that don’t define permanent structure. So the disulfide bond is the most critical to understand and manage in professional chemical services.