Well so far between what I've read and what I can remember from my experiences with it (a long time ago) is that is will begin to dissolve in water. I think the biggest concern would be time to set up. It may feel dry shortly but in that type of thickness might take a few days. But if you've got the time....
try picking up some, the smallest quantity you can buy, or come across, and do a small scale trial.
If I come up with anything further I'll let you know. In the mean time, if you get a chance to try it before I do, let me know how it works.
Mark.