I did find this

These are opaque pigments but I could possibly mix this in a small quantitiy to achieve a milky white color. I'm going to call them and ask... they also have a glow in the dark pigment that might be kind of funky!

On a side note, I hate to keep dangling this out here, still fighting the battle of bubbles, I tried to take a picture but they didn't show up, kind of hard to explain... anyway the last few weeks have been a bit busy for me. Works been hell with the lovegate virus, I just started a new kenpo class, and been helping a friend slowly move everything they own... anyway.. hopefully in the next few weeks I can get the button show on the road.