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20 Minute Labs: Homemade Rock Candy

rock candy logo | Yellow Scope


candy | Yellow Scope 20 Minute Labs

Are you a candy lover? Have you heard of rock candy? It's those delicious colored sugar crystals on a stick!

What if you could use science to make your own rock candy? That's just what we'll do in this month's 20 Minute Lab!

Note: Setting up the lab will only take about 20 minutes, but you'll have to wait about a day to see the first crystals, and a few days to get a store-quality hunk of candy!


  • rock candy supplies | Yellow Scope
    2 cups water
  • medium pot
  • 6 cups sugar (plus extra for rolling skewers)
  • spatula or large spoon for stirring pot
  • 2 wooden skewers or dowels (not metal)
  • 2 clothespins (or chip clips etc.)
  • 2 clear jars
  • food coloring (optional)
  • ladle

Notes: You can make as much or little as you like - as long you use a 3-to-1 ratio of sugar to water. It's important to have enough liquid to fill your jars.

You can also use string (attached to a stick or pen) instead of skewers.


    1. rock candy skewers | Yellow Scope
      Break your skewers down to size - they should be able to stick out of the jar by about an inch.

    2. Run the skewers under the tap to get them wet, then roll one end of each skewer in sugar. Set the skewers aside to dry completely. (If using string, you can skip this part!)

    3. With the help of an adult, add 2 cups of water to the pot and bring to a boil on the stove.

    4. Slowly add the sugar to the boiling water. Stir to dissolve. There may be a bit that won't dissolve at the bottom of the pot - that's okay!

    5. Let the sugar solution cool for about 10-15 minutes. Meanwhile, prepare your jars by making sure the insides are clean and dry.

    6. Add a few drops of food coloring to each one - whatever colors you like!

    7. Once the sugar solution has cooled for about 10 minutes, pour or ladle the solution into the jars, so it almost fills each jar. If you added food coloring, stir to mix.

    8. setup rock candy | Yellow Scope
      Now place the skewers into the center of each jar, sugar-coated side down. Make sure they don't touch the bottom or sides of the jar. Use clothespins to keep the skewer in place (see photos). 

      (If using string instead, tie the end around a pen and place the pen across the top of the jar, hanging the string into the jar but without touching the bottom)

    9. Leave your jars in a well-lit place for 1-4 days (4+ days for best results!) and observe the changes!

      days rock candy | Yellow Scope
    10. Remove the skewers and now, unlike most science experiments, you can eat the results! (But not the skewers of course - be careful not to poke yourself!)
    rock candy | Yellow Scope


    rainbow rock candy jars | Yellow Scope

    If you don't see any sugar crystals on your skewer, try again and make sure that:

    1) The skewer was fully dry before submerging (the skewer in the red jar was not dry enough, all the sugar fell off and dissolved right away!)
    2) the solution is completely saturated with sugar, and
    3) the solution cools down enough before the skewers are added.


    crystal | Yellow Scope

    Your delicious rock candy is actually a beautiful crystal. Crystals form when molecules fit together in an organized, repeating pattern.

    The process of crystallization is when molecules transition from randomness to uniformity!

    There are many different types of crystals found in nature, but crystals are generally formed in three ways:

    1. Diamonds and emeralds, are formed when liquid rock (magma) slowly cools and hardens.
    2. Other crystals, such as snowflakes and frost, are formed when water evaporates (dries up) and crystals are left behind. (Try our Snow Trees 20 Minute Lab to see for yourself!)
    3. Still other crystals form when a supersaturated liquid that has a dissolved mineral in it, cools. The crystals in this experiment were formed in this way.

    Growing crystals from hot water:

    white rock candy crystals | Yellow Scope

    By heating the water, you were able to dissolve more sugar than you could at room temperature. Hot water molecules are farther apart so they have more space to hold the sugar. This extra capacity for dissolving is called a supersaturated solution.

    As the solution cooled, the water molecules moved closer together, so sugar came out of the solution (out of being dissolved) and began to form on the skewer in crystal form.

    The sugar that you rolled onto the skewers themselves acts as a kind of 'seed', a starting place for the crystals to latch onto and grow. (If you used string, the string itself is fibrous enough to serve as the starting place for the crystals to grow.)

    The size and shape of the crystals depends on how fast the solution cools. When solutions cool fast, you get smaller crystals because they have less time to organize. Slow-cooling solutions tend to form larger crystals.


    Let us know how your experiments turned out! Share your photos and results with us on Facebook, Twitter, Instagram, or send us an email to We love getting your messages!

    For more exciting experiments, check out our Yellow Scope science kits on the Shop tab of our website!

    Chelsea Schuyler
    Chelsea Schuyler