I use activated charcoal externally as my natural deodorant. But this takes practice to make sure you don't go out in public with a tank top on a blackened arm pits!
About 20 minutes before I shower I apply a mixture of activated charcoal and water that I keep in a jar (say 1 teaspoon of charcoal to 2 teaspoons of water) to my armpits and let them dry with the charcoal on them. 20 mins later when I shower, I use a MICROFIBER cloth to remove the activated charcoal from my armpits. It doesn't always wash off easily so you must use a microfiber cloth, which is soft and won't scratch your armpits. And voila! No need for deodorant and lasts all day. Try it please in the morning and let me know what you think and don't get mad at me if you forget to wash it off and get weird looks. Me? Never! Heh heh.