I need to paint over royal icing... and I need it to be grey.. storm clouds n all. How do i achieve this look? just take a tiny bit of black and dilude w/ vodka?

any suggestions?

White and Black airbrush colors mixed?

I always use the white color from americolor mixed with a little black and paint it on.

mmm i don't have any white! any alternatives? it's the storm of the century out there right now.. i'd hate to brave the snow for some white color...