COS Extra Strength Formula is the safest and most effective way to reverse an undesirable hair color application. In just 20 minutes, COS corrects hair color by shrinking the dye molecules, allowing you to simply wash them away. Our unique formula is bleach-free and ammonia-free; COS will not have the damaging effects of bleach or ammonia based products. COS is so gentle that you can recolor your hair the same day.
