Courtesy of TIGI
It seems like every brand has a line of sulfate-free shampoo now. Why are sulfates so harmful to my color and Keratin treatment in the first place?
Keratin doesn't bond the hair like tradition perms or relaxers. Instead, it provides a coating on the hair strand which keeps the hair straight. The sulfates in shampoos break down the coating and cause the hair to revert faster. The same rule applies with hair color, sulfates tend to strip the color faster from your follicle.