• Question: what is glass made of

    Asked by jjfarooq to Dalya, Derek, Sarah, Tim, Tom on 19 Jun 2011.
    • Photo: Tim Millar

      Tim Millar answered on 16 Jun 2011:

      Silica from sand, heated to a high temperature and allowed to cool

    • Photo: Derek McKay-Bukowski

      Derek McKay-Bukowski answered on 16 Jun 2011:

      The main ingredient is silicon dioxide, which comes from sand, as Tim points out. However there are other ingredients as well.

      Glass makers add sodium carbonate, which I believe is so that the glass is easier to form and so that it doesn’t need such high temperatures to manufacture. They also add other metal oxides (aluminium, calcium and magnesium) to make the glass more resistant to chemicals.

      There are also various trace compounds, either for stability, or to colour the glass.

    • Photo: Sarah Thomas

      Sarah Thomas answered on 16 Jun 2011:

      Also glass can be made in nature: it can be formed when lightning strikes sand or soil! They are called fulgurites and are hollow glass tubes. They are formed when lightning with a temperature of at least 1,800 °C instantaneously melts the silica and fuses grains together. It can also be formed by volcanic eruptions and meteorite strikes.

      (I saw this in Sweet Home Alabama!)

    • Photo: Tom Crick

      Tom Crick answered on 19 Jun 2011:

      Glass is a non-crystalline solid material, usually brittle and optically transparent (you can see through it!).

      Glass is usually made by heating silica (silicon dioxide) and cooling to remove bubbles and imperfections.

Comments