Due to the high grade of European Remy Human Hair used in our units, you can change the color with no damage. As professional stylists, we suggest going from light to dark if a color change is needed. Just like your own hair, we don't ever suggest to our color clients to use bleach. Bleach alters the integrity of the hair. It's really a technical skill to provide a successful bleach process so please make sure you consult with your stylist before coloring at all. We color our units for thousands of customers with very successful outcomes but not all coloring techniques are the same with each stylist. IF THE COLOR COMES OUT NOT MEETING YOUR EXPECTATION IT IS NOT THE FAULT OF THE PRODUCT, IT IS THE FAULT OF THE STYLIST.