Begin with your hair wet or dry. Measure 1/2 cup baking soda and combine it with up to 1 1/2 cups warm water. Stir to dissolve the baking soda. Slowly pour this mixture over your hair and scalp, saturating it completely. Massage the baking soda and water mixture in your mane for about three minutes before rinsing with warm water.
Add 1/2 cup apple cider vinegar (you know, the brown stuff, not the clear type) to 1 1/2 cups warm water, and stir. Pour this mixture over your hair just like the baking soda solution. Massage it into your tresses for 3 to 5 minutes. Don't panic if you smell like a salad -- it's only temporary. Rinse with lukewarm water until the scent of vinegar fades and the water runs clear. If your hair has been previously colored, some color will be lost down the drain. Remain calm. (Hyperventilating now would be counterproductive.) This is actually a good thing, as your new color will look richer in the absence of buildup.
Shampoo your hair as normal. This step lifts out the last traces of buildup loosened by the baking soda and vinegar rinses. Lather twice, rinsing well each time. That squeaking noise that you hear is the sound of clarified hair, baby!
Apply a moisturizing conditioner to your hair. It may seem counterintuitive after stripping your hair of buildup, but the vinegar and baking soda rinses have removed some natural moisture along with the buildup. Moisture should be replenished to keep hair healthy. This single application of conditioner won't be enough to cause more buildup before your next coloring treatment. Rinse the conditioner out completely and detangle your hair. Remember that you won't be washing your hair again until 48 hours after your hair has been colored. Minimal styling products should be used leading up to coloring your hair. If you need them, use a light touch.
Dry your luscious locks, and style as you prefer. Notice that your hair feels softer than usual due to the baking soda and vinegar. These products deep cleaned your hair and scalp just as well as any costly clarifier. You now have a "clean slate" upon which to apply the color of your choice!
Although it may be tempting, avoid trying to expedite the process by mixing the baking soda and vinegar together. Remember elementary school science? These two substances when combined will "erupt" just like the fake lava in your fifth grade model volcano! Keep the two mixtures apart, and rinse your hair well between applications.
Amber-colored apple cider vinegar is recommended for removing buildup, but white distilled vinegar will work if dark vinegar isn't available. Apple cider vinegar is slightly stronger and will work faster. If you're using white vinegar as a rinse, you may need to apply it twice.