In his latest video, Andy George explored how to make his own eye glasses. In order to make these, George contacted Westminster’s resident survival expert Professor Lewis Dartnell to ask what materials you need to make a glass.
Professor Dartnell explained: “For glass you need silica which you can get from sand. You need something to help you melt that silica at reasonable temperature in a kiln and that’s called a flux. You can use soda ash or potash as a flux, which you can get from seaweed. And lastly, you need lime, which you can get from coral, sandstone or chalk.”
Professor Dartnell explained that potash can also be extracted from hardwood ash, instead of seaweed: “Timber collects potassium carbonate or potash, as it was known through history. It is a slightly different compound but it performs exactly the same function as a flux for helping to lower the melting point of your silica to make a glass.”
In a second video Andy George caught up with Professor Dartnell to show him his first attempt at making eye glasses. The first make had turned out green-tinted in colour and very opaque with the lenses full of tiny bubbles. To stop this Professor Dartnell suggested leaving the glass in the kiln for longer so that the glass melts thoroughly and to repurify the potash in his next trial.