5 things you didn’t know about...vitreous enamel signage
Credit: AJ Wells. Signage on the London Underground, such as the roundel, is made from vitreous enamel.
1. A highly durable material, vitreous enamel is a thin layer of powdered glass fused to a metal base, usually steel or cast iron.
2. After a fire at King’s Cross underground station in 1987, it was decided that materials used on the underground needed to be fire-resistant, including the signage, so vitreous enamel was used.
3. AJ Wells & Sons Limited, UK, a family-run manufacturer of vitreous enamelled signs and cladding products, has been making signs for the London Underground since 1990.
4. The base material for the sign, usually steel, is sprayed with an enamel ground-coat consisting of powdered glass, quartz, clay and oxides suspended in water. It is then fired at around 800°C so that the glass fuses to the base steel.
5. Properties of vitreous enamel include a longer lifespan, an anti-graffiti surface, corrosion resistance and durability.
To find out more see the upcoming November issue of Materials World.