My 9 YO and I did some fun experimenting yesterday to figure out the best way to make bath bombs. As a starting point, we tried a few recipes off of the internet. The first was was crumbly and smelled too strongly of olive oil, and the next one was equally tricky to work with. After our first two failures, we looked at our results and decided to omit the water in the recipes, using just coconut oil to hold the mix together.  It worked well! Here’s the recipe we came up with. You may have to  tweak it a little by adding a tiny bit more oil to make the perfect bath bomb mixture!

1 cup baking soda

¼ cup cream of tartar

2 Tbs. coconut oil, melted to liquid

food coloring

empty contact lens case

metal spoon

-Whisk together baking soda and cream of tartar. Slowly drizzle in coconut oil, mixing immediately. Stir for several minutes until you get a nice even mixture that holds together when you press it between your fingers.

-Separate the mix into 3 or 4 bowls, and add a few drops of food coloring to each bowl. Mix again until color is incorporated.

-Press the bath bomb mixture into empty contact lens cases and gently tap the backs with a spoon to remove fizz tablets. It may take a few tries to get the hang of it! If they don’t stick together, try adding a little more oil and mixing again. Dry the bath fizzies on a plate or cooking sheet and package in cellophane bags or pretty baking cups for friends and family. Use your fizz bombs within a few weeks for maximum fizziness!

–Older kids can make larger “bath bombs” using molds for round ice cubes (which we found at Target.) Double or triple the recipes, gently press some mixture into each side of the mold, and mound a little extra on each side. Press the mold together to compress the bath bomb mixture into a single ball. Tap one side gently with the back of a spoon and gently open the mold to release that side of the sphere. Hold it in your palm and repeat with the other side to release the entire bath bomb from the mold.

The science behind the fun: The chemical name for baking soda is sodium bicarbonate, and cream of tartar is potassium bitartrate, or potassium hydrogen tartrate. When you mix them together in water, you create a chemical reaction that forms carbon dioxide gas bubbles! It’s interesting to note that at temperatures below 76 degrees F (25 C), coconut oil is a solid, but that at temperatures above this, it melts into a clear liquid. How does this affect your bath fizzies? Will they work in cold water as well as they do in warm water? Try it!