Rock candy is fun to make, especially for kids! It is a simple sugar candy, and you can watch the crystals form.
- Gather your supplies. You'll need at least one glass jar, a paperclip and a skewer or other stick for each jar, string or thread (cotton works best), water, granulated sugar, and food coloring. You can also add flavoring extracts, if you want. The number of crystals depends on the number of jars you use, and you'll need more of each ingredient if you're making more rock candy. You can start with 2 cups of sugar and 1 cup of water. As long as you use twice as much sugar as water, it should work.
- Prepare your materials. Wash the glass jar thoroughly. Cut a length of thread a few inches longer than the height of the jar, and attach it to the center of your skewer, pencil, or other stick. Attach a paperclip to the end, which will weigh it down in the water. Wind it until the thread hangs about an inch from the bottom of the jar. Then wet your thread and roll it in sugar. This layer will give the sugar solution something to stick to. Set it aside to dry while you make the sugar mixture.
- Make the solution. Boil the water in a medium-sized pan. Then, add the sugar one cup at a time, stirring to make sure it dissolves. Continue to stir and boil the mixture until all of the sugar is dissolved, and then remove it from the heat. Make sure that you have used all of the sugar, or crystals may not form. Add any flavoring extracts or food coloring you are using at this point. You should only need 2 or 3 drops of food coloring to achieve a bright color. Be careful as you are boiling the water.
- Setting it up. Allow the sugar mixture to cool for 10 minutes, then pour it into your jar. Lower the string until it hangs about an inch from the bottom, and balance the skewer on the top of the jar. Then, place it in a cool place where it can sit undisturbed. Cover the top loosely with plastic wrap or a paper towel.
- Wait for crystals. Crystals should start to form within 2 to 4 hours, but you should leave it for 2 to 3 days for large crystals to grow. Do not disturb the jar until the crystals are done. Allow it to grow until it is the size you want. Then remove it from the jar and allow it to dry.
- Enjoy. If you want to keep your crystal for later, wrap it in plastic wrap.
Making rock candy, or sugar crystals, can be a lot of fun, and they're tasty, too! The crystals that form on the string are the same as sugar crystals, on a much larger scale. As the water evaporates, the crystals form on the string.