Metallic tinting
In the early days of glass-making, nobody knew how to change or remove the natural colour of glass. Materials were experimented with and their outcomes explored. It was discovered by accident that certain substances gave the glass vibrant colours and others removed the colour. It is now known that metal oxides can create specific tints. Some of these combinations have become more widely known than others. ‘Cobalt blue’, for example, is the colour produced by adding small volumes of cobalt to molten glass. Early glass makers found that red was a particularly difficult colour to make, as it faded quickly. The successful metal was discovered to be small amounts of gold, and today you will notice that red glass can still be more expensive than other hues.
Chrome oxide is used to produce the green glass often found in beer bottles