Famous How Long Can You Keep Mixed Hair Color References. Once you mix your hair dye with a developer, you’ll have to either use or dispose of it within one hour. Web here's how to figure out how often you can dye your hair.
Learn about hair dye expiration dates, how to tell if your hair dye is expired,. Yes, mixing two hair dye colors (or more!) can certainly be done! Web yes, you can keep unused permanent hair color as long as it has not been mixed with a developer, such as peroxide.
