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Make a strong pot of black tea. Place the black tea in a large bowl. Soak your hair in the tea for about 15 minutes. Wash your hair. Repeat every day for two weeks. Try a variation.
Allow it to cool down to a temperature where you can put your fingers into the tea and move them around without it hurting. Ensure that the bowl is large enough that you can fit your hair into it. Allow the product time to absorb into your hair. Rinse the product from your hair using lukewarm water. It will likely take about two weeks for your hair to look darker. After that, you may be able to maintain the color by soaking your hair once a week. Depending on the quality of your hair, it could return to its lighter color sooner. A variation on this method is to steep 3 heaping tablespoons (44.36 ml) of loose black tea leaves and 1 heaping tablespoon (14.79 ml) of rosemary leaves in 4 cups (960 ml) of boiling water for about 45 minutes then let it cool. After shampooing and rinsing your hair, pour the mixture over your hair. Let it sit for at least 30 minutes under a plastic cap, then rinse it out with lukewarm water.