Kids, did you ever wonder why the snow in movies never seems to melt?  You too can make a version of fake “Hollywood” snow using a common polymer. The fake snow is non-toxic, feels cool to the touch, lasts for days, and looks similar to the real thing.  All you need is water and the polymer called sodium polyacrylate.

Please note:  All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.

Procedure:

1. You can harvest the polymer, sodium polyacrylate, from inside disposable diapers or you can buy crystals in a garden center that are used to help keep soil moist.  For the first route, carefully cut open one or two diapers and separate the beads that are inside from the cloth fibers.
2. Just one or two teaspoons of the beads are enough to get started. Place them in a disposable cup and add some water, then mix the gel. Add more water until you have the desired amount of wetness. The gel will not dissolve, or melt. It's just a matter of how 'slushy' you want your snow.
3. Sodium polyacrylate 'snow' feels cool to the touch because it is mainly water. Place the fake snow in the refrigerator or freezer until well cooled to make it very realistic. If it dries out, you can rehydrate it by adding water.  If you want drier snow, you can add more polymer or reduce the amount of water the polymer can absorb by adding a small amount of salt.

Tips:

1. Fake snow is non-toxic, as you would expect from a material used in disposable diapers, but it is not edible.  When you are done playing it is safe to throw away.
2. Sodium polyacrylate is also found in fire-control gels, those toys that grow when you add water, and floral gel. The super-absorbent chemical is sodium polyacrylate [monomer: -CH₂-CH(CO₂Na)- ], which was invented by scientists at Dow Chemical Company and results from polymerizing a mixture of sodium acrylate and acrylic acid.
3. How does sodium polyacrylate absorb? Read the second link below for the details. 

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Kathleen Carrado Gregar, PhD, Argonne National Labs 
[email protected]
January 2012

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References:
Anne Marie Helmenstine at About.com: Chemistry
http://chemistry.about.com/od/chemistryhowtoguide/ht/fakesnow.htm
http://chemistry.about.com/od/howthingsworkfaqs/f/diapers.htm