Chemical Texture Services Practice Test

Heat drives the chemical reaction in an endothermic perm. The perm solution acts as a reducing agent that breaks the hair’s disulfide bonds, and this reaction requires heat to proceed efficiently. By applying heat, the processing happens faster and more completely, allowing the hair to take the shape of the rod as bonds reform. Without sufficient heat, the reaction can be slow or incomplete, leading to a weaker or uneven curl. Heat does not dry the hair or stop processing; it actually accelerates and can strengthen the curl by ensuring the bonds are properly broken and reformed around the rod.