Head to the kitchen and find a small bowl. Scoop 2 tbsp. of baking soda into the bowl.
Add 1 tbsp. of water to the baking soda and stir it with a spoon. Keep stirring until you make a thin, creamy paste. Add a few more drops of water if the baking soda is not creamy.
Bring the bowl with you into the shower. Wet your hair and scoop out the baking soda paste with your fingers. Just scoop it out and plop it on your head.
Massage the baking soda into your hair just as you would shampoo. Don't expect it to lather up like shampoo though. The grittiness of the baking soda is what will help lift out residue on your hair so you won't be needing any suds.
Let the baking soda sit on your hair for five minutes while you shave your legs or serenade yourself. Rinse it out afterward with warm water. Dry and style your hair as normal.
For an even cleaner shine, rinse your hair with apple cider vinegar. Dilute 1 tbsp. of apple cider vinegar in 1 cup of water. Tilt your head back and pour the rinse over your hair after removing the baking soda. Leave the apple cider vinegar in your hair for three minutes before rinsing it away with cool water.
Make sure you close your eyes during rinsing because the baking soda can burn if it gets in them. If the baking soda does get in your eyes, flush them with cool water for 15 minutes. If they continue to burn, call your doctor.