How to Make Rock Candy. Making rock candy - which is actually just sugar crystals on a string - can be a remarkably enjoyable and edible science project, as well as a tasty treat. Follow these simple steps to have a batch ready in no time.
Sterilize the glass jar and paper clip by boiling both in water for a few minutes.
Tie a short piece of kitchen string to the middle of a pencil or Popsicle stick.
Attach the paper clip to the end of string. (The clip will weigh the string down - this is important later.)
Moisten string lightly and roll in sugar (this helps the crystals form on the string).
Place the pencil or stick over top of a jar. Make sure clip is in the bottom of jar and the string hangs straight down into jar.
Heat 1 cup water to boil.
Dissolve 2 cups sugar in boiling water.
Add a few drops food coloring if you like.
Pour sugar syrup into jar and leave for 2 to 3 days or until crystals form on the string.