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Make Your Own Rock Candy

Created February 10, 2021
Colorful rock candy on wooden sticks
Rock Candy isn’t just delicious, it’s chemistry! Sweets like Rock Candy are made through a process called crystallization.

Sugar crystals form when you create a supersaturated solution of sugar and water — that just means there's more sugar than can be dissolved in the boiling water — and let it cool. Depending on how you handle the solution and how long you let it cool, sugar crystals can form in many different sizes and shapes. For Rock Candy, we let the solution cool for several days to form large sugar crystals.

In the scientific method, you always start with a question. For Rock Candy, you might ask, what affects the growth of your sugar crystals? What can I do to control the way my Rock Candy grows? Can I change the color? Can I add flavor? When you think about your question, ask yourself what you want to learn from this experiment.

After you have your question, you can head to our Learn page to study up and form your hypothesis — which just means what do you think the answer to your question will be?

Now it’s time to test your hypothesis!

Prep Time

  • 30 minutes

Tools & Materials

  • Clothespin or long clip
  • String & pencil, wooden skewers, or swizzle sticks
  • Wooden spoon
  • Small saucepan
  • Wax Paper
  • Paperclip or washer (if using string)
  • 4 – 6 clean, narrow glasses (must be glass)
  • 2 cups water
  • 4 cups granulated sugar + extra for dipping string or sticks
  • Food coloring
  • Natural flavoring (this is optional, but you can try peppermint, strawberry, cherry, orange or any flavor you like — this is your experiment!)

 

Directions

Step 1

Add 2 cups of water to a small saucepan and bring it to a boil over medium heat. Slowly add 4 cups of granulated sugar, about ½ a cup at a time, and use the wooden spoon to stir during each addition of sugar. Once the sugar is completely dissolved and looks clear, bring it to a vigorous boil. Remove from heat and cool for 15-20 minutes.

Step 2

Get creative! Add food coloring to the mixture or, if using a natural flavoring, add a couple drops at this time. Once the solution has cooled, pour it into the clean glass jars. A tall and narrow glass works best. Fill the solution close to the top and cover with a piece of wax paper to keep it clean while you move to the next step.

Step 3

Prepare the string, wooden skewers or swizzle sticks. If you have all three, try a batch with each and compare the final results!

If using string:
Tie one end of the string (twine or cotton) to the middle of a pencil and let it hang. Look at the glass and cut the string to roughly 2/3 of the depth of the glass (you want to give your Rock Candy room to grow, so make sure it doesn’t touch the bottom of the glass). Tie the paperclip or washer to the bottom of the string to work as a small weight. Carefully dip string into the sugar solution. When fully saturated, remove the string and roll it in the extra sugar. Lay string flat to dry on wax paper for about 5 minutes, making sure it’s nice and straight.

If using wooden skewers or swizzle sticks:
Carefully dip the wooden skewers or swizzle sticks into the sugar solution. When fully saturated, remove the skewers or swizzle sticks and roll it in the extra sugar. Lay skewers or swizzle sticks flat to dry on wax paper for about 5 minutes.

Step 4

Next, if using string:
Dip the sugary string into the glass with the pencil laying over the rim of the glass and the string with paperclip or washer hanging into the solution.

Next if using wooden skewers or swizzle sticks:
Place the dried skewers or swizzle sticks into the center of each glass. Once in place, clasp the clothespin or clip to the top of the wooden skewer or swizzle stick. Make sure the stick is in the center of the glass and raised so it doesn’t touch the bottom.

Step 5

Now it's time to let science do its work! Once you’ve completed the steps above, gently move the glasses to a place where they will be safe. Allow them to sit for up to 2 weeks or longer, depending on how big you want your Rock Candy to grow. During that time, be very careful not to move the glasses so the Rock Candy doesn’t break.

Step 6

When the Rock Candy reaches your desired size, set aside another piece of wax paper. Carefully crack the sugar on the surface of the glass and remove the string, wooden skewer or swizzle stick. Set it on the wax paper and allow it to dry before taking a crunchy bite.

Draw Your Conclusion

Examine how it worked: What worked? What didn't work? What could you change next time to alter your results? Will you try again?

Share your results below!