Brew a strong pot of coffee, preferably espresso, and let it cool. Shampoo as normal and rinse thoroughly. Then pour some of the cooled coffee over your clean hair and massage it into your scalp, along the length, and down to the tips. Repeat until you have used the whole pot.
Collect your hair into a shower cap and let the coffee work for at least 20 minutes. Rinse with cool water to remove excess coffee. If your first application is not as dark as you’d like, you can repeat the process twice a week to layer the color and achieve a deeper and darker hue.