2/2/2024 0 Comments Natron wood productsThe resulting colour and opacity from a given composition also may be controlled by the temperature and redox conditions inside the furnace. Opacity can be due to bubbles in the glass or the inclusion of opacifying agents such as tin and antimony. The most important contributions are from iron, copper, cobalt, manganese, tin, antimony, and lead. A colourant or opacifier – These can be naturally present in the glass due to impurities in the raw materials or can be deliberately added to the melted glass as minerals or as slag from metalworking processes.These minerals may already be present in varying quantities in sand. The most effective is lime (CaO) but alumina (Al 2O 3) and magnesia (MgO) can achieve this to some effect. A stabiliser – to stop the glass dissolving in water and increase corrosion resistance.Calcium oxide (lime, CaO) can also act as a flux. Post-Roman Islamic glassmakers reverted to using sodium-rich plant ash, while in Northern Europe, a method using ash from wood was developed to provide potash (K 2CO 3) as flux. In Roman times the mineral natron was used, a naturally occurring mixture of alkaline sodium salts, sourced from the Wadi El Natrun area of Egypt. In ancient times, the ash of sodium-rich plants growing in arid areas around the eastern Mediterranean provided soda (Na 2CO 3) as flux.
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