Hi folks, I have used sodium bicarbonate(NaHCO3, baking soda) as a deodorant for 20 years. Just wet a finger, dab it in the powder and then rub it around the armpit. I think it works because NaHCO3 is basic. Increasing the pH makes life hard for the bacteria. The alkaline environment also might neutralise the volatile(and smelly) organic acids that the bacteria produce. The sodium salts of these acids would not be volatile. The effect is instantaneous. The only side effect I've noticed is that your armpit hair becomes a bit lighter over time!