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Make Your Own Fireworks: Exploding Sidewalk Chalk

Have you ever wanted to make your very own fireworks? Independence Day is coming up, and we’ve got a fun, safe, and kid-friendly way to do just that!

(Added bonus – most of the materials you need are probably sitting around the house and the prep work takes only 10-15 minutes!)

You’ll need:

  • An adult to supervise the fun
  • Zip-top or closeable sandwich bags (medium to large bags work best)
  • Cornstarch
  • Vinegar
  • Food coloring or liquid watercolors
  • Baking soda
  • Paper towels – cut into squares

Another great thing about this experiment is that the measurements of the ingredients aren’t critically important. Feel free to experiment with different measurements and find what works best for you. We do recommend filling the bag at least 1/3 of the way with liquid chalk. The more full your bags are, the bigger the “explosion” will be!

First, prep your bags:

In a zip-top or closeable sandwich bag, mix the following:

  • A few teaspoons of cornstarch
  • Enough vinegar to create a thick liquid consistency. Start small and slowly add more vinegar as you see fit.
  • A few drops of food coloring or liquid watercolors. Make them as creative and colorful as you’d like!

Best of all, you can mix them right in the bag! It’s easy and there’s no mess to clean up. Kids will have fun “squishing” the bag to mix the ingredients together. You may want to mix several bags at once – when the kids start exploding them, they’ll want to do more. Prep once, and play for a long time!

Note: If you leave the bags sitting too long before exploding them, you’ll need to re-mix them just before you’re ready to play. Over time, the cornstarch will begin to drift to the bottom.

Next, make your baking soda “bombs” to add in:

In the center of a square piece of paper towel, pour a few tablespoons of baking soda. Fold the paper towel around the baking soda to close it up. Set it aside until you are ready to begin creating your fireworks. Again, the measurements aren’t critical. The more baking soda you use, the bigger your explosion will be. Feel free to experiment with different amounts.


Ready, Set, Explode!

When you’re ready to play, head outdoors to an area you don’t mind getting a dirty. A sidewalk or driveway works well.

Toss a baking soda bomb into one of your bags. You must seal it very quickly. (It may be helpful to have each bag mostly sealed beforehand, and then quickly slide your baking soda bomb into one corner of the top of the bag.) Your bag must be completely sealed or it won’t work right. Even a small pinhole can keep this experiment from working correctly.

Once the bag is sealed, shake it up really good and then quickly sit it down. Keep the bag away from your face (or anything you want to keep dry and clean).

The bags will begin to slowly expand, getting bigger and bigger until they finally POP! Repeat over and over with new bags and new baking soda bombs.

Once the bag pops, let your child play in the liquid sidewalk chalk for more hours of bonus fun!

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One comment

  1. We had great time trying this!!!!

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