The action that breaks the hair's internal bonds in a permanent wave is performed by the:

In a permanent wave, the waving lotion (processing solution) softens and breaks the hair's internal disulfide bonds so the hair can take the shape of the rod or tool. After processing, a neutralizer is applied to reform (rebond) the bonds in the new curled position and stop the chemical action. Both steps are essential: processing to break bonds, neutralizing to reset them. Understanding the basic two-step chemistry of a perm — process then neutralize — is core chemical-texture theory on the exam.