How Does It Work
So, you made a beautiful (and delicious) work of art using the Stained Glass Sugar activity but, do you know what happened?
Stained Glass Sugar, or sugar glass, is created when you dissolve sugar in water and heat it to 300-310℉ (149-154℃). This is called the “hard crack” stage of candy making. You’ve made what a chef calls a reduction by boiling away excess water to concentrate flavors and ingredients. As the water boils off, both the temperature and the sugar concentration rise. At this point of heating, the sugar concentration in the syrup is about 99%.
Sugar dissolved in water will normally just crystalize back to sugar again. The addition of the corn syrup to the solution prevents this from happening. Corn syrup holds the dissolved sugar molecules in suspension in the solution. The last ingredient, cream of tartar, separates the original, complex sugar crystals into glucose and fructose, sugar’s simpler components. Adding food coloring prior to hardening creates the “stained glass” look you wanted. Light passing through the translucent (allowing light to pass through it) sugar glass will show off the colors and patterns you spread around in it.
A note about temperatures: The temperatures in this activity are for sea level applications. At higher altitudes – as in Denver, CO, USA at about 5300’ (1615 m) above sea level – subtract 1° F from each given temperature for each 500 feet (152 m) above sea level you live. In Denver, you’ll get hard crack candy at about 289° F (143 ℃).
In the brown-liquid stage of candy production at around 338° F (170℃), the sugar concentration is 100%. The liquefied sugar turns amber or brown in color due to caramelization. The sugar is beginning to break down and form many complex compounds that contribute to a richer color and flavor. Caramelized sugar is used for dessert decorations and can also be used to give a candy coating to roasted nuts.
