Make Rock Candy
What you'll need:
- Jar (you will want something reasonably wide, so that there is adequate room for the candy to grow on the dowel)
- Wooden skewer/dowel or coffee stirrer
- 3 cups sugar
- 1 cup boiling water
- Food colouring
- 1/2 tsp vanilla or other flavour extract (optional)
- Wet the dowel most of the way up. Coat the damp portion with some extra sugar. Let dry as you prepare the sugar mixture. This step will help kickstart the crystallization process on the dowel.
- Pour the boiling water into a microwaveable jar or container and stir in approximately half the sugar. Stir until dissolved.
- Slowly, add the remaining sugar, stirring to dissolve after each addition. If there is still sugar at the bottom, you can heat the mixture in the microwave for 1 minute increments, until all the sugar is dissolved. Dissolving all the sugar will take some time.
- Allow the mixture to cool for 20-30 minutes, then pour the mixture into the jar, and add food colouring and extracts.
- Place the dowel into the sugar mixture so that it is around 1 inch from the bottom of the jar. Fix it in place with the clothespins. Make sure the dowel is centered in the jar. Only place one dowel in a jar if doing multiple.
- Cover jar with plastic wrap and place in an area where it will not be disturbed much.
- Let sit and wait for the crystals to start forming. This can take a few days.
- Once the sugar has crystalized enough to your liking, take the candy out of the syrup and let it dry (hanging over something to catch any drips) before eating or storing in plastic. If there is a layer of crystals at the top of the jar, that is perfectly normal. Just break it up to remove the skewer.
How does it work?
Water has a limited capacity to dissolve other things (like sugar) into it. But, when it is heated, it can dissolve more than when it is cold. When making the sugar solution, we added a lot of sugar! Because we were using hot water, we managed to dissolve more sugar into the water than we could with cold water, so we are able to create a mixture that is oversaturated with sugar. When it starts to cool, all that sugar is no longer able to stay dissolved in the water, and it starts to crystalize again. Because we coated the stick in sugar, the new crystals will start to grow on the stick until we get a crystalline structure!