Combine ¼ cup cornstarch and ¼ cup baking soda in place in an airtight container.
For brunette dry shampoo instructions:
Combine ¼ cup cornstarch, ¼ cup baking soda and 1 tablespoon cocoa powder. If you have darker brown hair add another tablespoon of coca powder and it will make the mixture darker. I used the tablespoon to stir the mixture but if in an airtight jar you could just shake it to combine the ingredients.
Notes
Dab on the powder at your roots and brush through. If it shows too much get out your hair dryer on high and flip your head upside down.