A touch-up is a simple procedure when the color is faded but maintains the tone and the shape requires no modification. In those cases, you may apply the brown color directly.
Since color changes over time as a natural process, for me, most of the time a retouch means "a correction”. During the consultation, it is important to establish that if you are doing a touch up you can not be 100% responsible for the final result, because you are working on a pre-existing basis.
When you see that your client arrives with reddish, bluish, grayish, or violet eyebrows you can not simply apply brown color on top. If you do it, the color that she had, will appear again. For this reason, you must neutralize it before applying the desired brown color. Of course, there are more complicated cases where you need to modify the shape as well, but this is another topic of conversation.
In general terms, you must remember that you have to neutralize a color with its complementary color. In the color wheel, the complementary colors are opposite each other:
- Orange complements blue, and
- Yellow complements purple