Summer of Science: Rock Candy

So far, this experiment, making rock candy, is my daughter's favourite. It took a lot of patience but when it was finished (it took one week) she was rewarded with candy that she (well, we) had made ourselves. Rock candy is beautiful to look at, and you can make it with plain sugar or you can add food colour and flavour extract. I let my little scientist pick, and she chose banana extract (that's a thing, believe it or not, that you can find with other extracts in the baking department) and yellow food dye.

You'll need a clean jar, a medium to large sized saucepan, a straw or chopstick (or other stick-like thing), a pipe cleaner, sugar and water. You will also need another clean jar or drinking glass, because you have to change the sugar water mixture daily for at least the first three days.

What you do is combine three cups of white sugar with one cup of water (you will not be eating three cups of sugar; in the end you pitch quite a lot of it). You stir it constantly over medium high heat until it boils. Take it off the heat and keep stirring until the sugar is nicely dissolved. Then you add your colour and extract, if you're using it, and pour the mixture into a clean jar. Wrap a pipe cleaner around the straw or chopstick or whatever you're using, until it dangles down to nearly the bottom but not quite of the jar. You want to balance the straw on the top of the jar. It should look like this:

I realize that this is not an appealing colour. Moving on.

You will need to put a paper towel over top to keep dust out but still allow water to evaporate.

Right after we did this, I asked Jr. Scientist to draw a picture of what she thought the crystals would look like. She thought they would look quite different than they really looked like, so that was kind of fun to find out.

The next day, or even later on in the day, you will need to scoop the crystals off the top so the water can still escape. Every day for at least the first three days you will need to transfer the mixture to a new container, because you want the crystals to attach to the pipe cleaner, not the sides and bottom of the container. You also need to allow the water to evaporate, as I mentioned, and it's difficult to do that when you've got a sheet of crystals at the top. By the fourth day, we just let it sit in the the jar until it was ready.

One week later, or when you decide it's ready, you should put the candy on a plate to let it dry for at least two hours. Then it's ready to eat. It was surprisingly delicious. I made a small rock candy on a little skewer to see if it would stick as well to a smooth surface (it doesn't) and I ate that. It was like a marshmallow banana in flavour. Not bad. Definitely edible. My kid loved it. I think we'll try orange next time.

This is the finished product in all it's very yellow glory.