The aluminum foil that surrounds the powder charge effectively forms a Faraday cage around the charge and actually protects it against static charge rather than causes static charge.
A lot of folks have a misconception about being in a metal building during a lightning storm, a metal building is exactly where you want to be during a lightning storm, you are inside a Faraday cage and protected.
Here's a Faraday cage video.
http://www.youtube.com/watch?v=ve6XGKZxYxA