According to Matrix Celebrity Stylist George Papanikolas, people with dark hair—dark brown to black—have red undertones in their dark hair color. When strands are exposed to elements such as sunlight, hair lightener, perms or chemical straighteners, chlorine or hard water, those undertones emerge, causing rich, dark tones to appear tinged with red or a rusty shade. Treating dark hair that is showing unwanted red tones with a shampoo or mask that deposits a controlled amount of green dye gets rid of the red, and restores the hair to its original, rich, dark brunette hair color shade.

Neutralization 101

“To understand how this works,” explains George, “simply look at a color wheel. “The color wheel is a chart representing the relationships between colors. It’s a circle that displays the colors of the spectrum. It shows primary colors--red, yellow and blue; secondary colors--orange, green, and violet; and tertiary colors--yellow green, blue green, blue violet, red violet, red orange, and yellow orange. The colors adjacent to each other on the wheel are complimentary. The colors directly opposite will neutralize each other. If you look directly across from red on the color wheel, you see green. Therefore, we know green neutralizes or cancels out red. That’s why green dye is the solution for unwanted red tones in hair color.”