Yes, darker areas can be gradually covered with lighter tones, but it usually requires more sessions.

After the main cover-up, we continue with additional sessions once the skin has healed, gradually building lighter tones over the darker areas. In some cases, even very dark black areas can be brought up significantly toward a light grey.

Below, you can see session-by-session photos from one of my cover-up projects where I gradually lightened a very dark area almost to light grey.