Rock Candy

February 5, 2025 Update

The rock candy experiment was successful! 

Look at this beauty!

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Earlier this week as part of my candy course, I watched a video on how to make rock candy. Now, the method wasn't exactly new to me. I think most people are first introduced to this concept in grade school as a science experiment involving a supersaturated solution. But as I sat watching the demonstration, it occurred to me that despite knowing about this for the better part of my life, I'd never actually tried it myself. Clearly the time had come. Challenge accepted, Tony Morris!

The recipe called for more than three cups of sugar and I could see that the candy maker had syrup left in the pot after filling a jar, so I decided to cut the recipe in half as I was measuring out my ingredients. I probably made my life more difficult by doing that, but I also didn't want to create a lot of waste. I only had paper lollipop sticks on hand and imagined that would be unpleasant at best when eating the rock candy, so instead I used the blunt end of a bamboo BBQ skewer. I expected that I would only have enough syrup to produce one rock candy stick, but prepared a second just in case. Then I rigged up a few mason jars with post-it note "lids" to hold the syrup. Finally, I went into my handy tool kit -- a gift from my father when I first went off to university -- and pulled a clamp to suspend the skewer in the solution. Probably not what he was imagining when he gave it to me, but here we are. Armed with a thermometer, I prepared the solution.

Now, dissolving an obnoxious quantity of sugar into a very small amount of water is no easy task, but if you take your time, adding a little as you go, you eventually get it done. I was surprised by just how thick the syrup was. The sweet and sour bar mix I made a few months ago for a Halloween party couldn't hold a candle to this. I decided that green apple was the perfect colour-flavour combination and stirred the syrup to distribute the colour. Finally, I carefully poured the syrup into the jar, suspended the skewer in the syrup, and set it aside to do its thing for a few days. 

Within hours, I could see crystals forming, but it appeared that they were growing more rapidly than they should. On day three, I decided to open the jar and see what was happening. I certainly had crystallized sugar, but there would be no getting the candy stick out. What I had was a candy stalagmite. The texture would have made a great centre for a chocolate geode, but was definitely not what I was going for in this experiment.

As luck would have it, we then had a snow morning. And that meant take two for the rock candy. I thought I knew where things went wrong the first time, so I modified my technique a little and set up a clean jar ready to receive the sugar syrup. Immediately I could tell this batch had more promise. I left it  to cool without disturbing it. 

Twenty-four hours later, I could see a few crystals starting to form on the stick, much slower than the first batch. I took that as a good sign. 

Forty-eight hours later, the characteristic large square crystals were gathering on the stick. 

Seventy-two hours later, I posted this blog. I had hoped to have a final product by the time it went live, but sugar has a mind of its own and can't be rushed. 

When I finally do remove the rock candy from the mason jar, I'll update this post. I can't wait to try it!