How to Grow Valentine Heart Borax Crystals

You gotta love a classic science experiment, especially for Valentine’s Day! Growing crystals never gets old. These Valentine Heart Borax Crystals grow overnight and get even bigger after a few days, so they’re perfect for a science experiment the week of Valentine’s Day.

Grow these lovely Valentine Heart Borax Crystals for a fun science experiment this February. Kids will love customizing their hearts and watching the crystals grow.

The Science Behind Borax Crystals

Crystals are an amazing part of our natural world and a fun project for kids to do. Here are answers to a few questions I get when making crystals with kids.

What is a crystal?

A crystal is a solid whose atoms or molecules are arranged in a highly organized pattern. Table salt, snowflakes, diamonds, and sugar all form crystals. Every substance forms its own unique crystal structure.

crystals close up

How do crystals form?

Crystallization happens when liquids cool and harden into solids. In this project, we create a supersaturated solution of Borax in boiling water. As the solution cools and the water evaporates, the salt in the water drops out and forms crystals.

What is Borax?

Borax is a laundry additive used to get your clothes extra clean. Its chemical name is sodium tetraborate and it is a salt of boric acid.

Why use Borax in Borax Crystals?

We use Borax in these crystals because Borax makes large, chunky crystals relatively quickly. You could make these hearts out of other substances, but you’d have to be a lot more patient!

What other materials can you use to make crystals?

Lots of substances form crystals when you create a supersaturated solution. All types of salt, from table salt to epsom salt work. Sugar works too. This is how rock candy is made.

Valentine Heart Borax Crystals

Valentine Heart Borax Crystals Supplies Needed

  • Pipe cleaners in red, white, or pink
  • Scissors
  • Pencil
  • Borax powder
  • Water
  • Spoon
  • Large pot
  • Glass jar
  • Extra pipe cleaners or string
  • Magnifying glass (optional)
Valentine Heart Borax Crystals Supplies

Borax Safety

Using Borax can be done safely at home with a few simple guidelines. Always wash your hands after handling Borax and keep it away from any individual who puts non-food items in their mouth.

How to Grow Borax Crystals

  1. Create the heart shapes from your pipe cleaners. We folded our pipe cleaner in half, then folded it into the heart shape. Just carefully bend and mold until you have the heart shape. Set aside.
Form the pipe cleaner hearts
  1. Tie a string or additional pipe cleaner to the heart shapes. Tie the opposite end to a pencil.
Attach the pipe cleaner heart to a pencil

Make the Borax Crystals Solution

  1. Start filling your pot with water. Hot tap water won’t usually do it, so you will need to fill with water and bring to a boil. 
  2. Now, add the Borax powder. Add 1/4 cup of Borax for every 2 cups of hot water you prepare.
  3. Carefully stir the Borax to help it dissolve. Make sure it is dissolved completely. Remove from heat.
  4. Transfer the hot water mixture into your jar. Place the pencil over the top of the jar so the heart drops down into the solution.
Drop the pipe cleaner heart into a jar

Watch the Valentine Heart Borax Crystals Grow

  1. Allow the heart to sit for 18-24 hours. You will notice the crystals forming after a few hours, and they will be completely formed after 24 hours. The crystals will continue to grow for several days in the solution if you’d like a larger heart.
  2. Remove the pencil/heart from the jar. Snip away the string or pipe cleaner you use for hanging.
  3. Allow the crystalized heart to rest on a paper towel to dry. 

Your crystal hearts are now ready to be displayed! Look at them under a magnifying glass for a really cool science exploration.

Valentine Heart Borax Crystals

More Valentine Activities for Kids

Looking for more ideas for Valentine’s Day? Check out these art, STEAM, cards, and more!

25 Valentine Process Art Projects for Kids

25 Valentine Process Art Projects for Kids

Printable Valentines for Kids (and Adults!) Who Love STEM & STEAM

Printable Valentine Cards for Kids Who Love STEM & STEAM

And be sure to check out STEAM Kids Valentine’s Day!! 14 days worth of hands-on science, technology, engineering, art, and math projects for kids.

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