sugar on wood table,White sugar on a wooden background,Spoon with white sugar on the dark background
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Rock candy, which is composed of sugar crystals, is one of the oldest forms of candy. It is exciting for children to make, because the progress of the crystal formation can be followed day by day, building anticipation for the finished candy.

The production of the candy also provides a teaching experience, showcasing the process whereby a supersaturated solution--in this case, sugar and water--is unstable, and evaporation will cause the crystals to precipitate or form back into a crystalline structure with very little provocation. The process is usually slow, but you can make sugar crystals faster with the right stimuli.

How To Make Rock Candy Fast

Heat 2 cups water over medium heat in a saucepan until it comes to a boil.

Stir 4 cups sugar into the boiling water with a wooden spoon until the sugar dissolves and the solution turns clear. Continue stirring until the solution again reaches a rolling boil.

Remove the saucepan from the burner, and pour the solution into a heavy tempered jar, such as a canning jar.

Tie the heavy nut to the end of the string, and tie the other end to the pencil.

How To Make Sugar Crystals Form Faster

Speed up the formation of the sugar crystals by dipping the string into the sugar solution, coating it with sugar and allowing it to dry out for 24 hours.

By suspending the string in the solution, sugar crystals can attach to the string. Balance the pencil across the top of the jar, and drop the heavy nut into the solution, straightening the string.

Locate the jar in a warmer part of the house, such as near a heating vent, and also position a fan to blow over surface of the jar to continue to speed up the formation of the crystals.

Why do warm and moving air cause sugar crystals to form faster?

Warmth and moving air speed up evaporation of the water in the solution, causing the crystals to precipitate or form into crystals faster than normal.

Make sugar crystals in three to five days instead of the usual seven days or more.


Food coloring can be added to the solution to create colored candy.


If the solution gets on your skin, immediately run cold water over the affected area to cool the syrup. Seek medical help if necessary.

Be extremely careful when boiling and pouring candy. The heavy syrup will adhere to skin and create very bad burns.