Why is sodium picramate in hair dye?

Sodium picramate is used in hair dye formulations primarily as a coupling agent and color developer. It helps create a stable and vibrant color by facilitating the chemical reactions that occur during the dyeing process. Additionally, it can enhance the dye's adherence to the hair shaft, contributing to longer-lasting results. However, due to potential safety concerns, its use in cosmetic products is regulated in some regions.