Walker's mix is 100 grams of Ancient Sunrise henna from Catherine mixed with a mildly acidic liquid. He likes to leave it in at least 4 hours, followed by a thorough rinse, then indigo for another hour.
The last batch of indigo was really good and we're now getting true blue-black, exactly what he wanted! The texture of his hair has been great since starting henna - it had been dry and crunchy, especially his gray, and now it's soft, full and glossy.
This shot was taken about 4 weeks out so he was about ready for another go. His natural color is black with about 30-40% gray, mostly on the sides.