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NIH Tech Transfer

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Kids' Catalyst

STRIPED ICE

It’s cold out there! While you’re enjoying your winter, try this experiment to produce some Striped Ice. What you’ll need is:

1. Water

2. Minute timer

3. Two drinking glasses (made of glass, to see the effect better)

4. Patience

5. Liquid food coloring; you’ll need at least one color, but a great combination is red and blue.

6. Experiment sheet with the headings "Time" and "Color"

Now take your glasses and fill them with water. Using the food coloring, make the water in one glass red, and the water in the other blue—make sure the color is dark.

Put both glasses in the freezer, set your timer for an hour, and go play in the snow (or do some homework). You should see ice forming on the top and sides of the glass, usually in some extraordinary patterns. Wait until enough ice has formed that there’s a solid coat of ice on the inside of the glasses.

Chip away at the surface of the ice so you can pour out the water from each color into other, empty glasses. This extra water can be used right away–by pouring red water into the blue-ice glass, and vice versa. Check the time, and come back in another hour. Now you have an alternate stripe!

Experiment with timing, different size and shape of glasses, slanted striping, and colors. (Remember, of course, to write down all of your findings.) Don’t worry if you forget to come back in an hour—water freezes from the outside surface in.

Wonder how it melts, and what color it will turn into when it melts?

Keep warm, and no matter how much ice you have outside, you can make some really nice ice inside!

—Jennifer White