Make crystal hearts

Make crystal hearts

This is a fun science activity that will also yield some crafty Valentine's Day decorations.  Children will be fascinated by the overnight appearance of crystals on their hearts.

What you need:

  • 1 x pipe cleaner
  • 1 x paddle pop stick
  • small piece of string or wool
  • large glass jar or jug
  • 2 cups water
  • 6 tbsp Borax (bulk buying stores in NZ)

Number of players:



Shape the pipe cleaner into a heart.

Prepare the crystal growing solution in a jar large enough to accommodate your heart shape.

Stir about 6 tablespoons of Borax into boilling water until it stops dissolving.

Tie a small length of  string to the heart and then use the paddle pop stick as a prop to suspend your heart shape in the Borax solution  (see video.)

Leave it overnight.  Keep an eye on it, you'll see the crystals start forming after about an hour or so.

Why is it so?

Borax is a common laundry product that brightens clothes.  But when mixed with boiling water in large quantities, the solution becomes supersaturated.  Supersaturated solutions are unstable. As a result, the excess Borax will crystallize on any rough surface. 


  • Thanks to our sister company Kidspot Australia for creating the instructional video.

Leave A Comment