Spring Break Sneaky Science – Rainbow Rock Candy

Rock Candy

Spring break is here for many and if you aren’t jetting off somewhere warm then you are probably looking for fun ways to distract and entertain your kids. Rainbow Rock Candy is a fun project that will provide daily discussions of science without making your kids feel like they are back in the classroom. During the preparation and growing process kids learn a little about math, color mixing and crystals without even realizing it.

Rock Candy-1

What you’ll need

  • 6 mason jars (cleaned and dried)
  • Wooden or Bamboo skewers
  • Bag clips
  • Saran wrap
  • 9.5 cups sugar
  • 4 cups Water
  • Food Coloring (Red, Yellow, Blue)
  • Large pot
  • Wooden Spoon
  • Measuring cup
  • About 1 Tablespoon of sugar for starter

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Pour water and sugar into pot, set temp to medium high and bring to a boil over medium high heat stirring constantly. Once all sugar dissolves and solution has come to a boil remove from heat and pour equal amounts (or as close as possible) into the mason jars.

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Have the kids add food coloring to each jar using the guidelines on the package of food coloring or by mixing until you get a color you like. Be careful because the sugar solution is very hot! For really young kids have an adult do this step and involve the kids by asking how many drops they think it will take.

  • Red
  • Red+Yellow = Orange
  • Yellow
  • Yellow + Blue = Green
  • Blue
  • Blue + Red = Violet

Stir each color mixture and set aside to cool somewhere where the jars won’t disturbed or in harsh light.

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While the jars are cooling take your tablespoon of sugar and pour on a plate. Get the ends of the wooden skewers wet and roll them in the sugar solution. These provide the starter for the Rock Candy and give the new crystals something to grab on to. Set the sugared skewers aside to dry.

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After about 30 minutes put skewers into the sugar solution and use the Bag clips to suspend them about an inch from the bottom of the jar. Cover loosely with plastic wrap and then watch the crystals grow!

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After One Week

After 4 hours you should start to see some changes, if after 24 hours you don’t see any growth you can add a bit more sugar to the solution and reboil and add more sugar to your starter. You can also half this recipe and use smaller jars.

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Once the rock candy has grown large enough remove it from the jar and allow it to dry a bit. Then you can enjoy it, or wrap it in plastic wrap to save for later.

*Update* There was a significant crystal growth on the sides of my jar after a week. I removed the rock candy from the batch and microwaved the solution for 2-3 minutes in 30 second increments stirring and scraping the sides. Once most of the crystals were mixed back into the solution I set it aside to cool for 30 minutes. Once it was cool I put the stick of rock candy back in. I have seen significant new growth since doing this.

Some issues I ran into were:

  • Initially I started with 8 cups sugar/4 cups water but saw no growth
  • The first time around I put the skewers in too early and because the solution wasn’t cool enough the starter sugar slipped off my stick. This has lead to growth of crystals on the inside of the jar.
  • I wasn’t able to find a dark corner for my solution which inhibited its growth. It still worked, but I am going to have to let them sit another week, or reboil my solution using the current crystal growth as starter.

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  1. Listen2Lena says

    Wow! Loved reading through all the steps but am an impatient person by nature so would never be able to wait a whole week! Love your sweet little experiment!