Which relaxer type is typically more suitable for resistant hair?

Sodium hydroxide is commonly used in chemical relaxers specifically designed for resistant hair types. This is primarily due to its strong alkaline nature, which allows it to effectively break the disulfide bonds in the hair structure. Resistant hair, characterized by its density and texture that can withstand chemical processes, requires a relaxer that can penetrate the cuticle more thoroughly and alter the internal structure of the hair.

Sodium hydroxide has a high pH level, which means it can lift the cuticle layer more efficiently, making it easier for the chemicals to access the cortex where the hair's structural integrity is altered. This makes it particularly effective on coarse or tightly curled hair types that tend to be more resistant to chemical services. The other relaxers mentioned, such as ammonium thioglycolate, calcium hydroxide, and potassium hydroxide, are generally used for hair that is less resistant, and may not provide the same level of efficacy on very coarse or dense hair.