Sparkle Kitchen: Rock Candy
In this week’s At Home with Martin & Sylvia story, "A Frosty Walk", brother and sister wake one morning to see that everything in their yard is covered in shimmering frost crystals. It looks like a frost fairy paradise! When Daddy takes them on a walk to their neighbor’s house, they discover Jack Frost’s work along the sides of the brook, on the tips of every branch, and especially at the edges of a pond.
Like Martin and Sylvia, I love seeing Jack Frost’s handiwork. As with many bit of nature “magic”, though, frost has a scientific explanation that, while it can’t compare to fairies, is pretty neat all by itself.
Frost is formed when water vapor, which is in the air around us all the time, condenses to liquid water. This happens because cold air can’t hold as much vapor as warm air can. The water then forms crystals as it freezes—that is, changes from liquid to solid–and the shape of the crystals is influenced by the surface the water freezes on.
While the chemical process in getting there is different, you can achieve a similar crystalline result by making rock candy.
To make rock candy, you start by making a hot saturated sugar solution. Because hot water can take on more sugar then cold water, the sugar will begin to come out of the solution (or make a “precipitate”) as the water cools and evaporates, forming crystals. Once again, the shape of the crystals is influenced by the surface you give the sugar crystals to grow on.
The recipe below will make about three small pieces of rock candy—depending on the size of the jars you use—and is a fun science experiment for a frosty day.
Rock Candy
Ingredients
1 cup water
approximately 3 cups sugar
food coloring and/or flavoring (optional)
Directions
Wet three bamboo skewers or short pieces of cotton string, then dip them in sugar. Set them aside to dry.
Meanwhile, mix 2 cups of sugar and 1 cup of water in a saucepan over medium heat. Boil the water, stirring to dissolve the sugar as you do. Add the last cup of sugar and continue stirring. The third cup shouldn’t dissolve as well as the first two. If it dissolves easily, add more sugar until the mixture starts to look a little gritty.
Divide the sugar solution into three jars. If you want, you can add a few drops of food coloring or flavoring (maybe orange extract or vanilla—yum!), but that’s completely optional.
Then suspend a piece of sting or a skewer in each jar, leaving about an inch of space between the bottom of the skewer/string and the bottom of the jar.
Cover the jars loosely, leave them in a cool place, and wait.
You should start to get some crystals forming within a few hours, and even more will form if you leave the jars to sit overnight. In my experiments, while the crystals were certainly more defined around the bamboo skewers, eventually the whole jar turned to a crystalline slurry.
When your crystals have grown to your satisfaction, drain off any remaining water and allow the crystals to dry. Enjoy them right away or cover loosely with plastic wrap to save for later.
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About the Author
Meryl Carver-Allmond
The Sparkle Kitchen Series is created by Meryl Carver-Allmond.
Meryl lives in a hundred-year-old house near the prairie with her sweet husband, two preschoolers, one puppy, one gecko, and about ten chickens. While she's been writing since she could pick up a pen, in recent years she's discovered the joy of photography, too. She feels lucky to be able to combine those skills, along with a third passion — showing people that cooking for themselves can be healthy and fun — in her Sparkle Kitchen posts.
