The most commonly produced type of glass we encounter mainly in the form of window glass, glass bottles and food jars. The composition of approximately 71-75% sand, 12-16% sodium oxide and 10-15% lime creates a surface that is particularly smooth and pore-free, easy to clean and translucent. The only disadvantage of this type of glass is its temperature behaviour: if hot liquids are poured in too quickly, the glass expands and can burst.
For particularly resilient and durable glass, the proportion of lime and sodium oxide is reduced to a total of 4-8 % and 13 % boron trioxide and 2-7 % aluminium oxide are added instead. The addition of these substances makes the glass particularly resistant to chemical effects and high temperature fluctuations. That is why this glass is often found in industry, laboratories, the pharmaceutical industry or as lamp glass. But everyday objects are also made of this durable material: e.g. baking and casserole dishes, drinking straws for hot drinks or glass cups.
The name is a little misleading for this type of glass. Because, from a purely physical point of view, crystal glass is not crystalline. It was named after the similarity to crystals such as quartz, which came about through the refractions and colour effects due to the added metal oxides or ions (13 - 15 %). It is mainly used for drinking glasses, vases, bowls or decorative elements.