Growing crystals is a favorite science experiment of ours and these glow-in-the-dark crystals for Halloween make it all the more exciting!

Check out how to make these fascinating crystals below!  Then, grab our 30 Science Experiments your kids will love in our shop!

Getting Ready

To prep for these glow-in-the-dark crystals, I gathered a few supplies:

  • Pipe cleaners
  • Borax
  • Glow-in-the-dark paint
  • Fishing line (twine or yarn would work, too)
  • Pencils or wooden skewers
  • Scissors
  • Glasses or plastic container (one for each shape)
  • Liquid measuring cup
  • Heat safe mixing bowl
  • Blacklight (optional, but makes the glow brighter)

Glow-in-the-Dark Crystals

Once I grabbed all of my materials, I called my kiddos over and told them we were going to whip up glow-in-the-dark crystals.  They decided what they wanted to make, grabbed pipe cleaners and started to bend the them into shape.


I tied each spooky creation to a wooden skewer using fishing line.  (Even though the fishing line is a little tricky to tie, crystals won’t grow on it but they will on twine.)

I placed each shape into a glass jar and made sure it didn’t touch any of the sides or the bottom. If they do touch, the shapes will grow attached to the jar and could break a bit when you take them out.


We ended up making a dozen Halloween shapes and needed a ton of borax solution.  My 5 year-old, A, measured out 1/4 cup of borax per cup of boiling water and mixed the solution until the borax dissolved.

A has done a lot of cooking so I was confident in her mixing and pouring hot water safely, but obviously please use caution when letting your child work with hot, hot water.


To make the glow-in-the-dark crystals actually glow, A added about a 2-3 tablespoons of glow-in-the-dark paint to the borax solution and mixed until well combined.  We used orange for the pumpkins and pink for the bat.  She then poured the solution into the jars and lowered in the shaped making sure they didn’t touch the sides or bottom.


Since we have a blacklight, we also made a few glow crystals simply by using fluorescent and white pipe cleaners since white glows in black light.

Now all we had to do was wait.  Within an hour you could see some of the borax precipitating out, mostly on the sides and bottom but my kiddos had to hold off until the next day for their favorite part: revealing the crystals.  We patted them dry then headed to a dark room to see the results.

Super cool science for kids! Make glow in the dark Halloween crystals!!

Here’s what they look like with the lights on.  So sparkly and gorgeous, right?

Simple, fun kids science! Make glow in the dark Halloween crystals!

And here’s a side-by-side of a pumpkin made with just fluorescent pipe cleaners and one made with glow paint.  You can see they both glow but the one that used paint (on the right) is definitely brighter.  Without the blacklight, the one made with glow-in-the-dark paint does glow after a good charge but it was too faint to photograph well.

Super awesome science for kids. Make glow in the dark Halloween crystals.

My kiddos love making borax crystals but glow-in-the-dark crystals was infinitely cooler.  So cool they just had to take the spooky creations to bed with them that night.

The Science Behind It

When borax is dissolved in water, a suspension is created.  A suspension is a mixture that has solid particles (the borax) that are large enough for sedimentation {settling out}. As the borax begins to settle, it starts to crystalize on all the surfaces it comes in contact with – including the pipe cleaner shapes.  As the borax continues to settle out, it builds crystals on top of other borax crystals forming a thick layer.

More Mad Science

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  1. How did you get the two-colored pumpkin? Amazing!

    1. Hi Darsha,

      The 2 pumpkins were different colors becuase one used fluorescent pipe cleaners to get the glowing effect under black light and the other used glow in the dark paint. Hope you have fun making these!

  2. I was wondering, how did you get the stem of the pumpkin green?
    I plan on doing this with my preschool class!

    1. Hello Again,
      For the pumpkin with the green stem I just used a green pipe cleaner and an orange one for the pumpkin part. Whatever color pipe clearer you choose, that color will show through the crystals. I suggest doing a test run at home before doing this with a class. It’s not tricky or anything but there are some quirks. If you use yarn or anything with texture, crystals will grow on that. I use fishing line, which can be tricker to tie so I suggest having the fishing line tied on skewers or pencils and secured with tape before hand. The pipe cleaners also cannot be touching each other or the bottom or they will stick. Good luck and have fun!

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