Last Christmas, I received a curious gift: a tiny bag of white crystals labeled Fake Snow. "Just add water," it said. So I did. And the crazy stuff puffed up unbelievably, forming a white-ish snow-like substance. Even weirder, the bag indicated that the snow could be dried out and reused (!) -- I didn't try that part.
So what is fake snow? Apparently the powder I had was primarily sodium polyacrylate, a polymer that can absorb 200-300x its own mass in water. This polymer also shows up in diapers... READ ON