Which process involves breaking disulfide bonds in the hair?

The process that involves breaking disulfide bonds in the hair is chemical waving or perming. Disulfide bonds are strong bonds that form the hair's structure, giving it strength and stability. In a chemical waving or perming process, a chemical solution is applied to the hair, which penetrates the hair shaft and reduces the disulfide bonds, allowing the hair to be reshaped into curls or waves.

After the hair has been processed and the desired wave pattern achieved, a neutralizer is applied to reform the disulfide bonds in their new configuration. This is what allows the hair to hold the new shape after the procedure is completed.

The other processes listed do not involve breaking disulfide bonds. Straightening, for example, may involve using heat or chemical straighteners to alter the hair's texture but does not necessarily focus on disulfide bond breakdown in the same way. Hair coloring targets the pigmentation without altering the structure of the hair through bond breaking. Deep conditioning treatments focus on moisturizing and repairing hair but do not alter disulfide bonds, as they are designed to improve the overall health of the hair without changing its shape or structure.