Why is my hair color brassy?
First let me define brassy hair color. When hair has unrefined, unnatural or "jarring" tones of red, orange or yellow, it is often called brassy. There are several reasons that your hair may appear brassy after a color service or shortly there after, and various things that can be done to prevent this from happening in the first place.
Let me begin with how to prevent brassy hair color. When going lighter, have realistic expectations of how light your colorist can take your hair with haircolor (not lightener, I'll discuss that later). If you are a deep brunette, it is unrealistic to expect your colorist to produce a very cool or neutral light brown color that is a more than a couple of shades (level is the technical term) lighter than your own with a single process haircolor. This is true of blondes as well. When you try to lighten your hair more than a few shades you enter the dreaded brass zone. The zone where the pigments in the haircolor lose the battle of controlling unrefined tones. Your best bet is to ask your colorist to lighten your hair a couple of shades at most in order to control the “warmth” or unrefined red/orange or yellow that you perceive, depending on your natural haircolor. If you want to go lighter than a couple of levels, say from a dark blonde to a very light blonde, have your hair highlighted with lightener and toned to the cooler/ashier color that you prefer. This can be done during or after the application of your usual haircolor service. Lightener has the ability to lighten your hair quickly and effectively, "cutting" through the unwanted warm, brassy tones. Any remaining unrefined tones can later be toned down with a toner. You will “appear” overall lighter, dimensional and with no brass.
Even hair that appears perfect in the salon can soon go brassy if not properly cared for. Limit excess shampooing and always use a shampoo safe for color treated hair. I tell my clients to treat their hair color the way you would an expensive garment. Cleanse gently and not too frequently. You may also want to try one of several of shampoos that include pigment that help counteract brassy hair.
Have your hair color refreshed and toned (when necessary) every 4-6 weeks to maintain your tone true and on target.