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Lithia is a very powerful flux, especially when used in conjunction with potash and soda feldspars. In ceramics, lithium lowers thermal expansion and decreases the firing temperature.

Possible outlets in glass manufacturing include pyroceramic ware, namely Corning Ware^®, borosilicate glasses, lighting glass, soda-lime container glass, foam glass insulation, and ion-exchange glass. Although the major role for lithium in glass is as a flux in order to reduce the melting temperature and thus reduce fuel costs, it may be used to alter some important properties of the glass including viscosity and thermal expansion. It is a valuable component in glasses having a low thermal expansion where its use permits the total alkali content to be kept to a minimum.

Glasses containing lithia are much more fluid in the molten state than those containing proportionate amounts of sodium or potassium, and the successful use of lithia in glass making lies in the fact that much smaller amounts are required to produce a glass of the desired physical and chemical properties. Lower viscosity and faster melting can be utilized to improve glass quality in terms of fewer defects such as unmelted or partially melted raw material grains, and more rapid removal of small bubbles. Lower viscosity can permit the glass maker to run his forming machinery at a higher rate, or create more elaborate products such as some perfume bottles.

In frits and glazes, lithia is used to reduce the viscosity and thereby increase the fluidity of the coatings. This reduces maturing times and lowers firing temperatures. Small amounts of lithia increase gloss. Spodumene is an ideal raw material for introducing lithia into frits and glazes and, in porcelain enamels, lithia acts as a strong flux, serving to reduce firing temperature and time. Because of its low molecular weight, small percentages have a marked effect. Depending upon the compound employed, it can be used either in the smelter or in the mill. The excellent fluxing properties of lithia serve to improve the working qualities of abrasion-resistant enamels for dry-process cast iron. From 2-2.5% Li₂O have been used. In dry-process enamels, the lithia must be added to the frit batch and not as a mill addition. In electrical porcelain it also is of value in producing a glaze of high strength and resistance to weathering. More recently, crystallized glazes have been developed for coating low expansion bodies. The lowering of the thermal expansion coefficient to an almost negligible level by development of the beta spodumene phase is the basis for pyroceramic, oven-to-table ware.

In fully vitrified porcelain bodies, lithium minerals in combination with nepheline syenite or feldspar have been shown to significantly reduce firing temperatures.

The objective with montebrasite additions is to lower the firing times and temperatures which results in savings in many areas including: fuel; refractories; additional production capacity. Tests at McMaster University demonstrated montebrasite additions at the rate of 2-3% allowed a reduction in firing temperature of approximately 100⁰ C.

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