This Halloween salt crystallization experiment is a fun Halloween science project that you can do in the classroom or at home!
The kids loved this science experiment and it has been one of their favorite crystal experiments to date!
If you love science AND you love Halloween, you’ll love this science take on how to make witch crystals! It’s a super fun version for Halloween STEM activities!
In 24 hours, you can make your very own spooky salt crystal designs.
Halloween Salt Crystallization Experiment
Here is how to make witch-inspired salt crystal shapes! Follow along with our directions below to learn how to make your own spooky Halloween salt crystals!
What Shape are Salt Crystals?
Use our project as a jumping off point to make dozens of your own salt crystal experiments in Halloween shapes!
We made cats, hats, and brooms, but you could make jack-o-lanterns, potions, cauldrons, or anything else!
Salt is originally in crystal form. Salt will always take on a square shape when the molecules bond.
The salt will continue to build and make bigger square shapes as time goes by.
As the water evaporates, the salt molecules cling to the pipe cleaner, forming large salt crystals.
How to Clean Up Salt Crystals
One issue that you may get into when making Halloween crystals in a mason jar is that the crystals get too big to remove from the jar.
The best way to deal with this is to make your shapes small when you are forming them so you don’t have to break them to get them out.
Your crystal shapes will double in size, so make sure the pipe cleaners can easily fit into the mouth of the jar when you put them in the liquid.
You can also use wide-mouth jars to make the process easier.
What Do I Need to Make Witch Crystals?
We love creative STEM activities for kids, and making them holiday-themed is even more fun. We turned a classic salt crystals science project into a spooky-themed science project by making our shapes witch-themed.
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More Halloween STEM Activities
Try these other fun Halloween science projects this October! Kids will love the spooky nature of these science experiments.
Find more amazing Halloween STEAM activities in the Spooky science Halloween book
Halloween Salt Crystallization Experiment Directions
We first shaped our pipe cleaners into our witchy shapes. We made a hat, a broom, and a cat.
Tie a piece of yarn around the top of each shape. Suspend it from the mason jar so that it can hang freely without touching the bottom or the sides.
Pin a clothespin in this spot and lay the clothespin over the top of the jar, suspending the shape.
Boil about 3-4 cups of water on the stove. When the water boils, add as much salt as can mix in.
We ended up using almost a whole container of salt, but we did have some that would not dissolve, so my guess is about half of a salt container is enough for three mason jars.
Fill your jars with saltwater.
If you don’t have enough water to cover the shapes, dissolve some more salt into hot water and add that so that all shapes are completely covered.
Place your jars in a sunny location for about three days.
After three days, your shapes will be completely covered in salt crystals! Amazing!