A candy thermometer is needed to make candy jars.
Sweet glass is a sheet of transparent material that is formed by pouring heated sugar syrup into a mold. It is not a very attractive candy as it lacks a distinct flavor other than candy, and is sometimes used in candy decorations and displays. Sweet glass was used historically for stunts where people had to break windows. It’s relatively easy to make candy glass at home, as long as you have a sturdy pan and candy thermometer.
Sugar is a very interesting substance, especially when it is heated. By heating sugar and mixing it with various ingredients, people can change its chemical structure to create a wide range of shapes and textures. Some extremely talented candy makers can blow sugar syrups like glass blowers blow heated glass. Sugar can be made into bowls, cups, and a variety of other ways. These techniques require advanced skills, but sweet glass is relatively easy to make.
In films, sweet glass is an excellent replacement for a window as it is transparent and will shatter like a real window. The edges are much less sharp, however, making it safer to work around sweet glass than real glass. Candy glass can also be colored with paints to create a replica of a stained glass window. The main shortcoming of sweet glass is that it tends to warp in hot or humid environments and, as a result, needs to be used quickly.
To make a cup of candy, heat three and a half cups of sugar, two cups of water, one cup of corn syrup and a quarter teaspoon of cream of tartar in a heavy pot until it boils. As it reaches boiling point, most of the water will disappear, creating a very dense syrup. Continue boiling the syrup until it reaches 300 degrees Fahrenheit (148 degrees Celsius) and pour it into a mold. Be aware that sweet glass is brittle, so it’s not a good idea to make a single sheet and try to cut it.
Once the chocolate glass has solidified and cooled, it should be used as soon as possible. It will attract ants and other insects and will be subject to melting even in moderate conditions. If you need a glass facsimile for something like a holiday screen, you might consider more durable alternatives to sweet glass unless you know the screen will be kept cool.