- ½ C powdered sugar
- 2 ½ Tbsp corn syrup
- 4 Tbsp water
- Pinch cream of tartar
- Cooking spray
- Parchment paper
- Cooking thermometer
- Large saucepan
- Mixing spoon
- Baking tray
- Measuring spoons
- Measuring cup
- Prepare your baking tray.
Line your baking tray with parchment paper and coat with cooking spray.
- Create sugar mixture.
Combine powdered sugar, corn syrup, water and cream of tartar in saucepan. Stir until fully combined.
The kids can help measure out the correct amounts of each ingredient, help pour them into the saucepan and mix the ingredients together if heat has not yet been turned on.
- Bring sugar mixture to a boil slowly over low heat.
Adult-only step: Slowly (this is key) bring the sugar mixture to boil until it reaches 300° F (this is also key). If the mixture is brought to a boil too quickly, it will caramelize and turn yellow.
It can take anywhere from 35-50 minutes for the mixture to reach the target temperature. Be patient with it!
- Remove the sugar mixture from the stove and pour onto the prepared baking tray.
Adult-only step: Slowly pour the sugar mixture (now, sugar glass!) onto the prepared baking tray. Using the spatula, try to spread it across the baking tray evenly. The thinner your mixture is on the tray, the thinner the sugar glass will be.
But don’t touch it as the mixture is still very hot. Let it cool for 60 minutes before handling.
- Break formation into edible sugar glass pieces.
Lift the sugar glass off the tray and peel off the parchment paper.
Ask the children to stand back, then drop the sugar glass onto the baking tray (from a low distance away from the tray) and watch as it shatters into small shards, just as real glass would.
The sugar glass can be carefully sampled (just be careful – some shards may be sharp enough to cut, especially if the mixture was spread thinly on the tray).
*Extra sugar glass you wish to save should be stored in a sealed container. The sugar glass is hygroscopic (it attracts water from the surrounding environment), so left out and exposed to humidity, the sugar glass will quickly soften and lose its brittle quality.
Ensure before starting that the children involved in the activity understand:
- How hot the liquid will become on the stovetop: do not allow them close to that area to ensure their safety.
- That real glass is never ok to eat: this activity must be done with children who fully comprehend that eating real glass is never ok. When you make “edible glass” it’s ok to take a bite.
- The edible glass could be sharp enough to cut: edible glass may not be quite as sharp as real glass, but it can still be sharp enough to cut, so be very careful when handling.
Real glass is created by heating sand (which is mostly silicon dioxide) to 3090°F. When the molten sand cools, it transforms into an amorphous solid, which means the molecules are arranged in a disorganized structure (usually when things are solid, their molecules and atoms are arranged in an orderly structure). This disorganized structure makes amorphous solids transparent and brittle.
In this activity, we are simulating the creation of glass by melting sugar instead of sand. Just like sand, molten sugar turns into an amorphous solid (called edible glass or sugar glass), and has a glassy, translucent appearance.