Grow Your Own Crystals

  • By Anna Rothschild
  • Posted 06.09.17
  • NOVA

What should you do with the borax you have leftover from making slime? Use it to make crystals! Find out how on Gross Science.

Running Time: 03:38


Grow Your Own Crystals

Published June 9, 2017

If you’re like me, you probably have a ton of that household cleaner borax leftover from your last slime making adventure. So… what can you do with it? Use it to make your own crystals!

I’m Anna, and this is Gross Science.

Ok. To grow your crystals you’ll need: borax, pipe cleaners, string, food coloring, scissors, a dowel or a wooden spoon, water, a cooking pot, and depending on how old you are, parental supervision, because we’ll be using the stove and also borax can be quite irritating. So please try to limit your contact with it, or wear gloves if you prefer.

So crystals are anything made up of a bunch of molecules arranged in an orderly way. The molecules stack on top of each other, making these very geometric shapes. And, you actually probably interact with crystals all the time, in the form of salt and sugar.

Now, crystals can be made in a number of ways. Many of the gemstones that we love are made when hot lava from Earth’s mantle gets forced up through fissures in Earth’s crust. As it moves through the crust the fluid cools and is also exposed to great pressure. And when it hardens, crystals form.

Borax crystals, however, form when hot water with borax dissolved in it cools and evaporates. As it cools, the borax will form crystals if it has something to cling to. And for that, we’re using pipe cleaners. I’m going to shape mine into a coil like this, but you can experiment with different shapes. You just don’t want the pipe cleaners to be either too close or too far apart.

Once the pipe cleaner frame is complete, attach some thread to it, so that it can hang in your borax solution without touching the sides or bottom of the pot or heat safe container. It’s gonna need to sit around for a little while, so try suspending it from a dowel or a pencil or a wooden spoon if that works. Now it’s time to make the solution.

A certain amount of borax will easily dissolve in water. But to make these crystals, we’re gonna need to make what’s called a “supersaturated” solution, which means that we need to add so much borax that no more will dissolve. To do this, boil some water, I’m using about 7 cups, and then add your borax. To get a supersaturated solution continue adding borax until the liquid stays cloudy. If you want to make your crystals fun colors, now is the time to add food coloring. Then, turn the burner off.

I’m going to transfer my liquid to a heat safe container, but if you have a big enough pot I’d recommend using that cause it’ll be much easier to clean. Finally, suspend your pipe cleaner structure in the liquid. To make sure that the crystals are able to attach properly you might have to dunk the pipe cleaners a few times, to get rid of any air bubbles clinging to them. Then, cover the top with tin foil. And for the biggest crystals, it’s best to leave it on the stove overnight.

All right everyone, I know I said this took overnight, but I actually made some crystals earlier. So… dun dun dun dah! Here they are! Look how cool that is! This was just one attempt, but I’ve actually made some others, and you can really experiment with different sizes and shapes. But just remember that these are borax, which can be irritating, so you don’t want to handle them too much or use them as jewelry. However, if you seal them with something, you can totally use them as decorations in a craft project, or something like that. So please experiment, send me photos of what you guys create, and let me know how you like this experiment. Thank you so much for watching.




Host, Editor
Anna Rothschild
Writer, Illustrator, Animator
K Melvin
Camera, Moral Support
Marshall Johnson
Heartbreak Liar - Underscore
Music Provided by APM


Original Footage
©WGBH Educational Foundation 2017
Sal (close)
Wikimedia Commons/kevindooley
Sugar Cubes (7164573186)
Wikimedia Commons/david pacey
Cardinal Gems
Wikimedia Commons/Mario Sarto


(used with permission from author)
Squeak Pack/squeak_10
Bubbles Popping
Boiling Towel
Basket Creek
Produced by WGBH for PBS Digital Studios


Crystal and Glass Container
©WGBH Educational Foundation 2017


Want More Info?

Here’s a tutorial for making giant borax crystals. However, DO NOT heat pyrex directly on the stove. I did so with some… unfortunate results that ended with glass and hot borax everywhere:

Here’s some info on gem formation:

Cleaning instructions: If you can do the experiment in a cooking pot, you can add additional water and just reheat the borax so that it becomes liquid again. If you use pyrex or something else that can’t be heated on a burner, poor hot water into the container a few times to loosen the mat of crystals that forms, and then dispose of them.

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