Make Rock Candy

Your Challenge: Make rock candy by growing your own crystals! Rock Candy



1 cup water

3 cups table sugar

1 glass jar

1 pencil

A pot for boiling water

A spoon or stirring rod

Cotton or wool yarn

Food coloring (optional)


Here’s How:

1.Tie yarn or string to pencil

2. Measure and cut yarn to hang in jar without touching sides or bottom

3. Boil water in pot

4. Stir in sugar a spoonful at a time. Continue adding sugar until it will no longer dissolve.

5. Add food coloring for desired color

6. Pour solution into jar (try to keep undissolved sugar in pot)

7. Place pencil with yarn across the jar with string dangling in. If your string keeps sticking to the sides try using a paperclip to weight the end.

8.Set jar aside somewhere it will not be disturbed

9. Wait and watch your crystal candy grow! (It should take about a week)


Take It Further:

Try different color combinations or even try adding flavoring to your crystal candy!


How It Works:

As the sugar solution cools it becomes supersaturated, so it starts to changed from a liquid to a solid. It does this because the super supersaturated solution has too much solute (sugar in this case). It must let go of the extra solute and this in combination with the water evaporating gives us our precipitate (the rock candy). This is when our crystals form layer by layer, molecule at a time. Crystals are solids that have regularly ordered and repeating patterns of atoms, molecules or ions in three spatial dimensions. Specifically sugar crystal falls under the categorization of isometric, cubic crystal.


Fun Facts:

  • Rock candy originates from Iran and India where it is often used to sweeten tea [Resource]
  • In the Netherlands it is common to bake pieces of rock candy into a special white bread called Fryske Sûkerbôle [Resource]
  • Rock candy was initially popularized as a cold or cough remedy around 1880 [Resource]
  • The largest crystal in the world is made of limestone and is found in Chihuahua, Mexico [Resource]  


Related Careers:

Food Scientist, Chemist

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