The Science Behind Edible Glass

Simulate how to make glass using in your own kitchen. Watch it shatter just like real glass! Fun edible science for kids.

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The idea for this activity came about when Jewel asked how glass is made. We explained that glass is made in a factory, where they get lots of tiny little grains of the purest sand, and heat it up until it is so hot that it becomes molten, and then it turns into glass.

 

But the questions kept coming.   The next one was “What does molten mean?” We explained that molten is when something is so hot that it turns into a liquid. Different things become molten at different temperatures. Water becomes molten at 0^oC. Sand needs a much higher temperature to become molten.

 

“But why doesn’t glass look like sand?”

 

Hmm, that’s a trickier one to explain. Perhaps it’s easier to demonstrate. We’re not able to make actual glass in my own kitchen, but we can make a very close replica – edible sugar glass!

 

 

Just like real glass, sugar glass is made from tiny opaque grains (of, in this case, sugar) which when molten and allowed to cool, transform into an amorphous transparent sheet, which is solid yet brittle. What does amorphous mean? We’ll get on to that later. First, let’s try making the stuff. 🙂

     

The original recipe that we followed called for corn syrup, but that’s tricky to find in Australia, so we used glucose syrup instead. Since it’s mainly the water component which differs between these syrups, which will be boiled off anyway, I think you should be able to use either. You’ll also need some common household items like a large saucepan, spoon for stirring, baking tray, measuring spoons, etc.

3. Slowly bring the mixture to the boil, until it reaches 150^oC (300^oF)..
This part is best done by an adult – firstly because 150^oC is very hot. And secondly, because this part is not very exciting and requires a lot of patience. The key word here is to heat the mixture “slowly”. If you heat it too fast, it will start to caramelise and become yellow.

 

Once the water has boiled off, the temperature will start to rise. The amount of time this takes may vary – it’s more about the temperature reached than the time taken. A candy thermometer which clips onto the saucepan would be perfect, but Mr Banya used our cheap hand-held cooking thermometer, and that still worked just fine. For reference, it took 40 minutes for our batch to reach the target temperature.

 

4. Take the molten sugar glass off the stove and pour onto the lined baking tray.
Try to spread it across the baking tray as much possible – the thinner the mixture, the thinner your sugar glass will be. Don’t touch it! It will still be incredibly hot. Let sit for an hour to cool.

 

5. Call the kids over, because this is the fun bit!
Carefully lift the sugar glass off the tray, and peel back the baking paper. Notice that the opaque sugar has turned into transparent ‘glass’.

 

 

Drop the glass onto the baking paper, and watch it shatter into shards, just like real glass! (Be careful, some of those shards may be sharp enough to cut.) Taste it! It’s very sweet.

 

 

6. Store any left over sugar glass in a sealed container in the fridge.
Because sugar glass is hygroscopic (meaning it attracts water from the surrounding environment), it will quickly soften and lose it’s brittle quality if exposed to humidity.

 

   

   

  For more tasty science ideas, check out our edible science experiments page. Some of our favourites are:

• how to make fizzy sherbet
• homemade Anzac biscuits
• how to make homemade butter
• how to make curds and whey (or homemade ricotta cheese)

 

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