Making rock - 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.
- Skill level:
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Things you need
- 240 ml (1 cup) water
- 450 g (2 cups) sugar
- Food colouring
- Cotton strings
- Ice cream sticks
- A glass
- Paper and binder clips
Sterilise 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 ice lolly 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 colouring if you like.
Pour sugar syrup into jar and leave for 2 to 3 days or until crystals form on the string.
Tips and warnings
- Crystals should start to grow in 2 to 4 hours and continue to grow for a couple of days. For big crystals - fast - heat the sugar-water solution a second time and dissolve extra sugar in it.
- The sugar mixture is very hot and children will need adult supervision.