Glassmaking in the Laboratory

New chemical glass compositions techniques can be initially investigated in small-scale laboratory experiments. In the laboratory mostly pure chemicals 

Thermal expansion The thermal expansion properties, particularly the low expansions, are the primary properties that have been exploited commercially. The low expansion materials have been used for applications where thermal shock resistance is important such as cookware, stove tops, heat exehangers etc. They have also been used in applications such as mirror substrates where minimal thermally indueed distortions are important. Higher expansion materials have been used for sealing various metals and alloys. 

Thermal stability The maximum use temperature must be defined in terms of a time factor and degree of loading. The erystalline phase plays an important role, but the maximum use temperature is limited by the residual glass whieh may crystallize further or it may enhanee deformation by viseous flow. The glass ceramic materials are generally more refraetory than the eommon glasses but less refractory than the eommon oxide refraetories. 

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