Final answer:
Heavy conditioning prior to a permanent wave may cause weak curl formation. A basic reducing substance is used in the permanent wave process to reduce and rupture disulfide cross-links. Heavy conditioning can interfere with the formation of these disulfide bonds, resulting in weak curls.
Step-by-step explanation:
Heavy conditioning prior to a permanent wave may cause weak curl formation. In the permanent wave process, a basic reducing substance, such as ammonium thioglycolate, is added to the hair to reduce and rupture some of the disulfide cross-links. These disulfide bonds are responsible for holding the alpha-helices in the hair strands together. When heavy conditioning is done before the permanent wave, it can interfere with the formation of these disulfide bonds, resulting in weak curl formation.
For example, if the hair is deeply conditioned with a heavy conditioner that contains ingredients like oils or silicones, these substances can coat the hair strands and create a barrier, preventing the reducing agent from effectively reducing and rupturing the disulfide bonds. As a result, the new disulfide bond positions may not be formed properly, leading to weak or looser curls.
It is important to note that conditioning the hair is generally beneficial for its health and appearance. However, when preparing for a permanent wave, it is recommended to minimize the use of heavy conditioners or to avoid conditioning the hair immediately before the process to ensure optimal curl formation.