Henna is a semi-permanent, botanical hair color product that comes in red tones. Some companies use metals, oxidative dyes, or other plant pigments such as indigo, madder root, turmeric, or walnut to alter the shade of the henna.
Pick your henna shade wisely, because metals can be extremely toxic. Henna usually comes in powder form and is mixed with water, coffee, or black tea. It's applied to dry hair as a paste.
*Depending on the effect you desire, the processing time varies from 15 minutes to several hours with a cap and heat so bring a book.