How to Make Rock Candy on a String

Create rock candy on a string for a tasty treat and science experiment.

Watch sweet crystals of sugar grow on a string in just a week when you make rock candy at home. Strings of rock candy result from the string soaking in a supersaturated solution of sugar and water. According to the Exploratorium, both the supersaturated solution and evaporation contribute to the creation of crystals. Supersaturation means there are more sugar molecules than can remain in the water, resulting in some of them precipitating on the string. Evaporation over the course of the week further saturates the solution and pushes the sugar molecules onto the string.

Things You'll Need

• 2 cups of water
• Saucepan
• Whisk
• 4 cups of sugar
• 8-inch cotton string
• ½-inch diameter washer
• Pencil
• 1 pint glass jar
• Scissors

Instructions

1. Bring 2 cups of water to a boil in a saucepan.

2. Whisk 4 cups of sugar into the boiling water until all the sugar dissolves. Bring the mixture back to a boil.

3. Remove the saucepan from the heat.

4. Pour the sugar water into a 1-pint glass jar.

5. Dip the 8-inch-long string into the sugar-water mixture in the jar and allow the string to dry completely, which should take about 2 days.

6. Tie a half-inch diameter washer to one end of the dried 8-inch-long string, and tie the opposite end around the middle of a pencil.

7. Place the pencil attached to the string across the top of the jar and lower the washer into the bottom of the jar so the string stretches straight down in the sugar water mixture in the jar.

8. Leave the jar on a counter for one week to allow the sugar crystals to grow on the string.

9. Lift the pencil from the jar to pull the string out and cut the washer off the bottom of the string with a pair of scissors before enjoying the candy.

References

• Michigan Department of Natural Resources: Make Rock Candy
• Exploratorium: Crystals