How can chemicals relax, or straighten hair? Well first of all, as assumed, the chemical would need to be potent enough to do so. Both lye and “no lye” relaxers are very strong chemicals that work in the same manner by changing the basic structure of the hair shaft. The chemical penetrates the cortex or cortical layer (see illustration) and loosens the natural curl pattern. This inner layer of the hair shaft is not only what gives curly hair its shape but provides strength and elasticity.