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Few things are sadder than faded glory, especially when it’s on your head. Hair color works by coating your hair, not actually changing the color of your hair itself; it’s more a paint than an actual dye. Harsh shampoos can strip the coating off, fading the color until it looks lifeless and dull. A shampoo specifically formulated for babying color-treated hair is your best bet for increasing time between salon visits.
Color-safe shampoos generally don’t contain sulfites and other harsh chemicals that can strip the color out of your hair. All shampoos contain some sort of detergent, which sticks to water on one end of its molecules and to oil and dirt on the other. That’s why it cleans your hair better than plain water does. It grabs the oil and dirt and then hitches a ride with the water you use to rinse it all out. Color-safe shampoos are gentle enough not to also grab some of the color that sits on top of your hair.
Sunlight fades hair color, so lots of shampoos for color-treated hair have sun block built right in. This is similar to the sunscreen you use on your skin – it blocks some of the ultraviolet rays that cause damage. But, like sunscreen, the sun block in color-safe shampoo is not a magic shield. If you are going to be in the sun all day, wear a hat.
Dry hair looks dull, which can make the color look faded. Shampoos for color-treated hair have humectants, which draw moisture to your hair. They also contain conditioners to smooth down the little scales that make up the outside layer of your hair. This makes your hair reflect light better, letting your hair color shine.
Some color-treated shampoos have tints that refresh your hair color when you wash it. These tints are not permanent, so you can’t just use tinted shampoo instead of hair color if you want long-lasting results. But they will add a little boost to fading hair without damaging it or drying it out.