I tried pearl dust for the first time last night. I really wanted to make my entire cake shimmer. I obviously did something fundamentally wrong, though. I mixed it with vanilla extract and started painting it on with a small brush. First, I realized how long it would take me to paint an entire 8 inch square cake with a tiny paintbrush, but I also ended up with streaky lines. The color was too dramatic, as well. My fondant was soft pink and I just wanted a delicate shimmer. I ended up with a streaky, darker pink, mess. I wiped it off with a wet paper towel and gave up.
What's the trick?
use vodka or lemon extract instead it works great.
You can apply it dry and it won't be as heavy of look. Use a fluffy brush to do this like a make up brush and then you can apply as little or as much as needed.
Also if you do it wet, but you want the shimmer more subtle, you need to use much, much more liquid. I.e. you need to dilute your "paint." Helps with the streaking too.