Rock Candy

Rock Candy is one of my favorite treats, and when I heard you could make it at home, I was so excited! This recipe is easy to make and tastes delicious. Depending on how big you want your rock candies to be, it may take a few days for the rock candies to grow, but it is fun to check on the candies daily and see the sugar crystals form.

Rock Candy (adapted from The Spruce Eats)

• Total time: 60 mins
• Yield: 6-10 candies

Ingredients

• 2 cups water
• 4 cups granulated sugar
• 3 large glass jars or 10 small glass jars (small jars produce more candy)
• Pencils
• 6-10 candy sticks or wooden skewers
• To flavor with extracts: 1 drop flavoring extract per jar
• Optional: food coloring

Instructions

• Soak the candy sticks or wooden skewers in a bowl of water.

• Pour granulated sugar onto a plate so that it is covered with a thin film. Roll each candy stick in the sugar.

• Allow the stick to sit for about 10 minutes or until dry. Once they are dry, repeat the sugar coating process again.

• Place the water in a medium-sized pan and bring it to a boil. Begin adding the sugar, one cup at a time, stirring after each addition. You will notice that it takes longer for the sugar to dissolve after each cup you add. Continue to stir and boil the syrup until all of the sugar has been added and it is completely dissolved. Remove the pan from the heat.

• Allow the sugar syrup to cool for approximately 10 minutes, then pour it into the prepared jars.

• Add 1-2 drops of food coloring and 1 drop of flavoring extract into each jar. Stir the jars until the coloring is even throughout the solution.

• Lower a skewer into each jar until it hangs about 1 inch from the bottom. Fasten it to the top of the jar by taping a pencil to the skewer and laying it across the top of the jar. If you are using a spice jar, you can attach the sticks to the insides of the holes in the spice lid.

• If you are using a large jar, you can place two sticks per jar if they are at least 1.5 inches from each other and 1 inch from the side of the jar.

• Cover the jars loosely with plastic wrap or a paper towel. Place the jar in a cool and dark place.

• You should start to see sugar crystals forming within 2 to 4 hours. If you see no change after 24 hours, try boiling the sugar syrup again and dissolve another cup of sugar into it. Then pour it back into the jar and insert the string or skewer again.
• Allow the rock candy to grow until it is the size you want. Don’t let it grow too large, otherwise, it might start growing into the sides of your jar! Once it has reached the desired size, remove it and allow it to dry for a few minutes, then enjoy or wrap in plastic wrap to save for later.
• Serve and enjoy!

Now for the science!

When water is at room temperature, it can dissolve a certain amount of another solid. When you heat up water, its saturation point, or its ability to dissolve other solids, increases. Think about when you are making iced tea. If you try to stir in sugar while it is cold, the sugar falls to the bottom and does not dissolve the tea. When you are making hot tea, the sugar dissolves easily into the tea.

When we heat up the water and add sugar, we create a supersaturated solution, which means more sugar is dissolved into the water than would be able to at room temperature. When the sugar and water solution cools down, the water cannot hold as much sugar, so the sugar mixed into the water starts to become solid and form crystals. The sugar-coated sticks that were placed in the sugar and water solution serve as a “seed” on which the sugar crystals can form!