For storing balloons and keeping them from sticking together, especially if you blow them up by mouth. Otherwise they can tear apart when you try to reinflate them.
https://www.amazon.com/Harris-Diatom.../dp/B01LRMN9ZM
Unscented talc by itself works fine, but the duster spreads it out really thin and evenly without making a huge mess. To coat the outside, shake the balloons in a big ziplock bag. Then they can be put away without sticking so bad.