Homemade Rock Candy is incredibly easy to make, it just takes patience. There are so many variations using string, sticks, etc. We’ve taken bits and pieces of what we found online (and our own trial and error) and here is how we successfully made rock candy at home. My son has some growing in our window sill right now as a little project for Cub Scouts. He used a string and didn’t color his sugar water, but the result is the same as the rock candy we made before. For us, it is more fun to watch the crystals grow than to actually eat it. It’s a beautiful science project and treat all in one. To make rock candy on a stick, follow the directions below!
The first time I attempted homemade rock candy I used a 2:1 ratio and after 3 days of ZERO growth, I poured it all back and heated each individual glass of syrup over the stove again and added more sugar. I wouldn’t recommend doing that, it was a pain, but I didn’t want it to go to waste! I added a bit more sugar to it and it worked. So that’s why I would suggest definitely a 2:1 ratio and then adding a little sugar at a time until it starts to look a little cloudy. That is the point that it has reached saturation.
We used 8 cups of water and 18-20 cups of sugar and it made a lot. So you can definitely half the recipe or create as little as you like as long as you keep within the same sugar/water ratio. You are making a nice, sticky, sugary syrup. Mix until mixture starts to simmer. You do not need it to a rolling boil or bring it to a certain temperature with a candy thermometer. Easy.
Too much vibration Keep your crystal setup in a quiet, undisturbed location.
Contaminant in the solution The fix is to re-make your solution. The fix only works if you can avoid contamination (won’t work if your starting solute is the problem). Common contaminants include oxides from paper clips or pipe cleaners (if you’re using them), detergent residue on the container, dust or something else falling into the container.
Inappropriate temperature Experiment with temperature. You may need to increase the temperature around your crystals to get them to grow (increases evaporation). For some crystals, you may need to decrease the temperature (which slows the molecules down and gives them a change to bind together).
Here are more fun and easy science experiments for kids!