Peppermint Rock Candy

This all started with a post over on Eggton. Are you an Eggton reader? You should be, if you’re not. When I read the post about rock candy, it was in the days before I’d MET Katherine and Scott in real, actual, honest to goodness life. I liked them then. I super like them now. Eggton is even funnier, because I can say ‘oh that’s SO Katherine and Scott, hahaha’.

Never mind the fact that we only actually met for six hours. This is irrelevant.

So, one day, in those sadder, emptier days pre-meet, I read this post about Rock Candy. I thought, ‘hmm’. I did not know about rock candy, though a little investigation shows that it’s a totally normal thing in the US, and children make it for school projects. It seems to me that children in North America get to do awesome sciencey experiments, and here in the UK we just get to watch woodlice scurry on to the dark side of a bit of cardboard. I sense an injustice.

Anyway, rock candy is kind of a science experiment that you can eat, unlike a baking soda volcano or a tooth dissolved in a glass of coke, so I wanted to give it a try. I set up a Science Area (capitals fully justified).



In my Science Area, there are three pint glasses, each with two wooden skewers stood upright inside them and secured with a food bag over the top. The food bag also stops any interested flies getting into the experiment and changing that ‘edible’ status. The next thing I did was prepare the skewers for making rock candy, by wetting them and rolling them in some granulated sugar.



This ‘seeds’ the sticks, and gives the sugar crystals something to form around. I feel like it’s a similar thing to when water boils or champagne bubbles – the bubbles need a little imperfection to start off with. You can also do a very cool thing with ‘super cooled’ water, where you take it to below 0C but it’s not quite turned into ice, and then you give it a wee nudge to form a few bubbles and the water realises it’s supposed to be ice and you can watch a whole bottle transform itself from top to bottom. Fascinating; I did it by accident once with a bottle of Irn Bru. True story.

Anyway, the idea of rock candy is that it’s a way to form sugar crystals, watching them grow day to day. You start off with a really dense sugar syrup – I dissolved four cups of sugar in one cup of water. I wasn’t kidding about it being dense. You add the sugar one cup at a time to water that’s in a pot over a medium-low heat, and you can feel the difference between dissolving the first cup and dissolving the last. The fourth cup doesn’t want to dissolve, and the water stays just a teeny bit cloudy even after lots of stirring. That’s when you know the water’s saturated with sugar, and you add some food colouring and flavouring as you like. I used green colouring and peppermint essence.


From cloudy, sugary water…


…to clear syrup…


…to more sugar…


…to minty, green, foamy syrup.


I’m not too sure what that foam was or why it went away after a little while, but when it had gone I poured the syrup into my pint glasses, then propped up the seeded sewers inside. Over the next ten days, I took a photo on most days and then selected the ones that showed the growth of the sugar crystals most clearly. It was fun to watch!

After the ten days, there was a thick layer of hardened sugar on the top and bottom of each glass, as well as the rock candy skewers inside. There was also a lot of syrup left over, which I’ve bottled and keep on hand to sweeten cocktails at a moment’s notice. You just never know when a cocktail will appear, and need sweetening. I eased the sticks out as best I could and sat them on some greaseproof paper to dry. Here is the end result:



You can see where some candy was lost to the bottom of the glass. I feel like the fun is mostly to be had in the first few days, when you see the crystals forming. They didn’t grow as big as I’d hoped, and I also thought they might climb up the skewer a bit but that didn’t happen at all. Perhaps I’m too old for rock candy, and have lost my sense of wonder…? Perhaps just one stick per glass would have been better? Perhaps a warmer, drier climate would help things along, and that is why we never make it in this country because it rains ALL DAY LONG for ten months out of the year? It seems to have raised more questions than answers, this experiment.

The shapes are still cool to look at, and I have a Plan for what to do with the candy, too. What I certainly won’t be doing is giving it to children; making a sweet on the end of a sharp, pointy stick is not a child friendly thing to have done. I realise this now.




About Rock Salt

Seasoning while rocking out since 1983. View all posts by Rock Salt

5 responses to “Peppermint Rock Candy

  • Rin Simpson

    Love it. I did loads of fun edible experiments when I was growing up in South Africa, including this one, except we did it with string suspended from a pencil balanced over a jar. I think the hot climate made it so much quicker!

  • Eggton

    I ADORE YOU. That’s all for now–a tree is about to fall on my house so I should go (true story. More on that later.) But I just had to say that the parts about the woodlice and the fact that you made children’s candy on a SPIKE cracked me up.

  • thekalechronicles

    We also made it with string — avoids the pointy hazard, but no one I know ever thought to flavor or color it: it was just pure sugar all the way! Your post makes me want to go down to the kitchen and start various flavors.

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