After the brow glue is applied and your brows are brushed into your desired shape and style, "Brow Style" is applied with a cotton tip. This step helps to make the hairs softer and more malleable, in preparation for the setting solution that will do most of the lamination work.
In technical terms, Brow Style contains thioglycolate, which is a chemical that will open the hair cuticle, enter the cortex of the hair strand, and "begins the process of separating the bonds between the keratin clusters," according to Lash Perfect Beauty Bar. This cream was left on for 10 minutes before being wiped off, and I didn't feel any tingling or sensation whatsoever.
Image Source: POPSUGAR Photography / Ange Law