One of the safest ways to color a hair system without getting the color on the base material is to comb it onto the hair. This will allow you to have more control over the color and keeping it off of the base material.
When coloring a hairpiece it is a good idea to use a color that is one shade lighter than your own hair color. The hair in a hair system generally takes color a lot quicker than your own growing hair does. This will prevent the color on your hair system from getting darker than your own growing hair. In fact, it is a good idea to color your own growing hair the same day you color your hair system.
Here is a video that one of our clients made to show his method on coloring his hair system:
I hope this is helpful.
Have a great day!
Lisa | Hair Replacement Consultant | firstname.lastname@example.org