Interlocking Crystal Hearts : Grow Your Own Crystals

Are you a person who likes holiday themed science and STEM activities!? If so, this is a perfect activity for you and your kids to try. Make your children say ‘woww’ by growing beautiful heart crystals at home. This fun science and craft activity also works as a great science activity to bust the holiday boredom of your kids.

Crystal Heart go science girls

Growing crystal hearts at home is a simple science experiment for kids that require easily available supplies in the market. I promise you all that growing heart crystals at home will never fail to impress your kids.

My girls have done this cool science activity 4-5 times whenever they find their free time. Also they explore few science concepts every time they does this activity. This is a perfect activity for kids of 7 years old and to younger ones it is bit difficult to understand the science behind it.

Are you ready with your kids to show them little science activity that yields some fascinating and crafty Valentine’s Day decorations? Yes!! Then get into our topic and learn how to make interlocking crystal hearts using common household supplies.

Growing Interlocking Crystal Hearts

My little ones always love crafty experiments!! If there is something we can learn science along with craft!?? Super exciting and much more fascinating right!? This experiment is the one satisfied my wish to show my kids a satisfying and quiet easy activity that improves their craft science concept. The lovely crystals may look like sugary candy but they are not safe for consumption instead very much useful to make crystal ornaments during this festive season.

Magic ingredients you need to grow heart crystals

This is a fantastic craft experiment to do with children which requires a very few ingredients. I have listed the supplies you need to grow your own interlocked heart crystals.

  • Borax powder (a common household ingredient is the magical and main ingredient to do this craft)
  • Pipe cleaners
  • Boiling Water
  • Cutter

[*Product links are affiliate links. Your support is highly appreciated]What we Need


1) Firstly, shape the pipe cleaners into hearts. Cut the pipe cleaner (should be in good length) into half. Bring the two ends of the half together and twist in the shape of a heart. Use the other half to make another heart and combine the two hearts using a thread or glue. You can make interlocked hearts by making loops from pipe cleaners.

Different interloking shapes

2) In the same way, ask your child to make three circles. This is very easy to make interlocked circles.

3) Girls go crazy on jewelry and ornaments. Hence, my daughters used this activity to make their own crystal ornaments. Hence, I helped them by tying a long piece of ribbon at the end of interlocked heart shapes.

Interlocking Borax crystal hearts

4) It is always suggested to kids to put on the safety glasses while working with the chemicals which is a good habit. My two kids love to wear glasses whenever they get a chance which also give them a ‘real scientist look’.

Add Borax powder into glass

5) Keep the boiling water ready and start dropping borax powder slowly (can measure a spoonful for each turn you put in the water). Keep stirring while adding borax powder until it dissolves. The ideal measurement of borax and water mixture is 3 table spoons of borax for a 250ml water.

Add boiling water into glass

6) Now it is the time to immerse your interlocked hearts and leave it for next 24 hours to grow wonderful crystals.

Soak the interlocking shapes to borax water

7) During our first trial to grow heart crystals, unknowingly we dropped the pipe cleaners into the borax and water suspension touching the bottom. So we haven’t got any crystals. It was disgusting and a big failure. So make sure your hearts or any shapes are not touching the sides or bottom of the jar.

Shapes in Borax water

8) What to do in order to hold your hearts not to touch the sides or bottom of the jar? Tie them to a pencil or any horizontal stick types using a ribbon or a fish wire and slowly drop into the jar so that the pencil settles on the top of the jar edges. You can see this in the figures (to get an idea) we have attached.

9) Keep the jars in the safe place and let it settle for next 24 hours or overnight. Kids got fascinated by observing the progress through the sides of the transparent glass jar in front of their eyes.

It is like a punishment for me to make them sleep the night whenever we make crystals. 🙂 Finally I made them sleep by listening them some science behind the formation of crystals. Let me tell you also.

Next day morning, after woke up the first thing they did was looking for crystals on their hearts. Yes they did it! Finally very big crystals are arrived in our jar. My kids were very happy and excited to see them making their eyes big. Fantastic right!! J Once the growth of crystals is stopped you can remove from the jar and clean it with fresh water to join it in your ornaments collection. Now as I promised you I will tell you the science behind it.

Borax crystal heart

Interlocking crystal heart experiment for kids

Oh! I didn’t mention about the failure part of our experiment. For some reason, the crystals formed on two of our interlocking models didn’t look good. Failure is part of science experiments.. I think my girls learned it the right way. They took the result positively and started exploring with different shapes for the next experiment.

Failure crystal shapes

Science behind Borax crystals formation

Mixture of water and borax powder forms a super saturated solution. When the water is hot water molecules repel each other and move far away from each other. This creates more space for water molecules to hold more borax. As soon as the water gets cool, the water molecules again come closer and cannot hold the borax as much as they could when it is hot. Hence the borax powder gets dissolved as much as it can when the water is hot. This process is termed as ‘Super saturation’. The extra borax gets settled at the bottom of the glass jar when the water gets cool or else stick to the pipe cleaners forming crystals after few hours.

Crystals are hard to touch and could see with our naked eyes. Kids get more fascinated seeing them under a microscope or any magnifying glass.

Finally I could say these crystal heart experiment is the perfect combination of learning and creativity.

Why do crystals form with borax?

Hot water holds more borax molecules as the water molecules move farther apart and makes more room for the borax molecules to dissolve in the water. When the water gets cool and evaporates, or when there is no solution to dissolve, the excess borax molecules form a hard substance with flat sides called ‘crystals’. These crystals build on one another and may be small or big but all follow the repeated pattern based on it’s unique shape. When the gets cool, the water molecules move closer together and provides very less room for the dissolved molecules to hold on to water molecules. Hence, crystals grow faster in warmer temperatures than colder ones.

Can you make borax crystals in a plastic container?

Yes, you can grow borax crystals in a plastic container but it is not suggestible. As we are using hot water, the plastic cant withhold to the hot water temperature. If you still would like to grow borax crystals in a plastic container then make sure the plastic container should not melt or deform to the heat of boiling water. In case, your crystals get fused in the container, deal them gently to separate.

How do you make borax crystals to grow faster?

Growing crystals at home is much faster science experiment to fascinate your kids. To grow borax crystals faster, make sure you use heat safe container and hot boiling water. Basically you need to make a saturated solution and let it cool or evaporate to form molecular structures called crystals. Growing crystals using traditional methods takes several hours to form but there is a possibility to limit the time to two-three hours using different techniques. Borax crystals that are formed in less time are less resilient and finer.

Are borax crystals safe to touch?

Borax is not at all safe to touch. It causes burns when you are exposed very often. It even effect your airways while using it since it mixes with the air and when the air goes in to your respiratory tract, you may feel trouble breathing. It is a mild irritant but could be toxic when the kids touches and keeps in the mouth. It is not harmful when you use it in lesser quantities but extra doses of usage can cause the above mentioned issues.

Will borax crystals dissolve?

Yes, borax crystals dissolve in hot water. This is because hot water molecules repel each other and allows borax molecules to dissolve much faster and dissolves easily.

How to preserve borax crystals?

Borax is a mineral found naturally in our nature generally used for cleaning purpose because of its unique properties. Since the borax crystals are homemade and created in the water based solution, we need to protect or preserve them from moisture and humidity. You can keep them in another plastic or coat with an acrylic to protect the crystals not only from humidity but also from being shattered. Be sure to wash the crystals with the fresh water or let them dry completely before they go in to the container.

Some of interesting facts about borax crystals.

1) The first Borax came from the dry lake deposits in Tibet, China.
2) Borax is actually a salt naming Sodium Tetraborate (naturally occurring white mineral).
3) Borax is classified as sedimentary rock.
4) The process of crystals formation is known as crystallization.
5) The key fact in growing borax crystals is boiling water because hot water holds and dissolves more borax than cold water.
6) Borax crystals look so amazing and pretty when made into beautiful ornaments, decorative pieces and much more.

How long do borax crystals take to grow?

The rate borax crystals growth depends on three factors mainly i.e. supply of elements, mechanism of element transport, and degree of saturation point. However we need to wait overnight or 24 hrs to grow borax crystals in our home. As fast as the saturated solution gets cool, the crystals start growing and cling to the pipe cleaners (the arrangement made in the glass jar to grow crystals). If you are using a plastic container, you need to have lot of patience to see the beautiful borax crystals in your jars.

Interlocking crystal experiment for kids
Interlocking Borax Crystal Hearts
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