I'm helping my Haitian friend prepare for her wedding and she asked me to try to get some kind of face powder they use for special occasions that is supposed to prevent the sweat from appearing on her face...do you know what she is talking about?

Some women wih excessive sweating of the face use light talcum powder, or the compact foundation's loose powder. Stay away from heavy creams or face moisturizers as they clog the facial pores.
There are no other products out there for facial sweating, that I know of.

Ask me anything