Weathering powder question.

[snitcythedog]

Afternoon all,
I have a question for the experts.  I am currently working on the interior of a fantasy bakery and need to simulate the dusting of flour that would be all over the place.  The piece I am working on has been dry for forty-eight hours and was painted in craft acrylics.  I have a pack of weathering powders from a railroad company that includes a nice white that I thought would work. When the white is applied it bunched up into little clumps and did not dust or adhere to the surface.  All of the other powders still seem to work but not the white.  Next I tried corn starch and had an identical result with clumps and not sticking to the surface.  Tried again with flour and it did the same thing.  I was worried about it being too humid to apply the powders but since I tried different colors and they are still working I am unsure.  Does anyone have any ideas or product suggestions?   
Many thanks.

[Tarnegol]

It may be no better than what you have already tried, but my first thought was baby powder. If it doesn't work at least it'll smell nice!