Diaper Snow: Sensory Science

Deep inside diapers lies an amazing molecule that can absorb hundreds of times its weight in water. It is called sodium polyacrylate and is an inert, skin-safe polymer that can provide loads of fun sensory play. Read on to learn what it is, where to get it, and what to do with it!

Materials and Methods

Sodium polyacrylate can be purchased as artificial snow (click here for to buy) or harvested from an unused diaper. To do the latter:

  1. Cut the top cloth-like layer of the diaper (the part that touches the baby) right down the middle width-wise.
  2. Fold it on the cut, cut side down and put it in a plastic tub.
  3. Shake it until tiny white specks gather at the bottom of the container.
  4. Remove the diaper.
  5. Add water (with food coloring if you want) a little at a time and watch as the water is quickly absorbed into the growing mass.
  6. For a lighter texture, add less water, for a slushy texture add more water.

Discussion

Polyacrylate, on the molecular level, is like a long string of negative charges. The sodium, which is positively charged, sits on these negative charges all along the string, which allows the polymer to coil and tangle up. When water is added, it displaces the sodium and nuzzles up with the negative charges. This causes the polymer strand to unravel, not only increasing the size of the gel, but also exposing more negatively charged sites so even more water can bind. This is why you get so much absorbent bang for your buck.

What to do with it?

  • Sensory Bins
    • Add cups and molds and make sand castle-like creations with the slush form (more water)
    • Add small world toys, like evergreen trees and arctic animals, to play with the lighter form (less water)
    • Initially make the snow without coloring, then give the kids squirt bottles with colored water to
  • Magic Tricks
    • Make water “disappear.” Put the dried sodium polyacrylate at the bottom of an opaque cup, show that it is “empty”, pour water in, then flip the glass upside down. The polymer should absorb the water, expand, and stay inside the cup, making it look like the water disappeared.
  • Fake Snow
    • You can inexpensively buy enough sodium polyacrylate that you can fill a kiddie pool (or larger!) sized area with fake snow that kids can play in for a Frozen themed party or what-not.
  • Fluffy Slime
    • Add it to your favorite slime recipe for a whole new feel

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