Description Blue cobalt glass is a special kind of fire-watching glass, which is mainly used for fire-viewing by the potassium flame reaction in chemical laboratories. It is also used in many places in the industry (such as: cement plants, steel plants, industrial kilns). Features - Size: 5.00X5.00X0.50cm/1.97X1.97X0.20in - Material: Glass. - Blue cobalt glass is a kind of observation lens, which mainly plays a role of filtering and protecting. - The production process of blue cobalt glass is special. Special glass made by adding "cobalt blue" (the main component is cobalt metaaluminate: Co(AlO2)2) in the production process. - The addition of cobalt blue gave the glass a special blue color, so it was named blue cobalt glass. - When observing the flame color reaction of potassium, it is necessary to pass through the blue cobalt glass, because the potassium compound is not pure, and it is often mixed with some impurities, such as sodium (not easy to separate). - It is generally used in laboratories or industrial cement production, steel plants and other high-temperature furnace mouths.Packing list: 2 x glass sheets