You will recognise vitreous enamel as the material used to produce the now highly collectable advertising signs produced during the early 20th Century. The ‘Hovis’ and ‘Virol’ signs were part of the everyday street scene. Your cooker will almost certainly have a vitreous enamelled oven and the higher quality cookers will use it on the outer parts. Your cast iron or steel bath will have been vitreous enamelled. Less obvious are the storage silos on farms, usually blue or green; they tower over the surrounding countryside. Carl Faberge used enamel for his unique eggs and jewellery and the Battersea enamellers are famous for their copper enamelled boxes. These are just two of the better known groups of highly skilled artists who used this very special material.
The word enamel comes from the High German word ‘smelzan’ and later from the Old French ‘esmail’. The Collins English Dictionary defines enamel as ‘a coloured glassy substance, transparent or opaque, fused to the surface of articles made of metal, glass etc. for ornament or protection’. Vitreous enamel is specifically on a metal base. It is thus defined as a vitreous, glass like coating fused on to a metallic base. In American English it is referred to as Porcelain Enamel.
It should not be confused with paint, which is sometimes called ‘enamel’. Paints cannot be enamel. They do not have the hardness, heat resistance and colour stability that is only available with real vitreous enamel. Beware of companies or products implying the use of enamel. Check their credentials and warranties.
The glass will be applied to the metal by a various methods either as a powder or mixed with water. This is followed by heating in a furnace to a temperature usually between 750 and 850 degrees Celsius. This ‘firing’ process gives vitreous enamel its unique combination of properties.
The smooth glass-like surface is hard; it is scratch, chemical and fire resistant. It is easy to clean and hygienic.
Vitreous enamel can be applied to most metals. For jewellery and decorative items it is often applied to gold, silver, copper and bronze. For the more common uses, it is applied to steel or cast iron. There are some specialised uses on stainless steel and aluminium.
The durability of the early advertising signs, still showing the brilliance of the original colours after a hundred years, is one of the best examples of the long-term colour stability of vitreous enamel. Compare them to signs, for example road signs, produced in less durable materials which fade and become shabby. Some of the early vitreous enamelled relics date back to the 13th Century BC and the colours are still as vibrant as the day they were produced (see our page on Enamelling History). If you want something where the colour will never fade – use vitreous enamel.
Following the disastrous King’s Cross fire, where combustible materials underground were the major cause, the specification of vitreous enamel for both decorative and functional parts in underground applications is now universal. It cannot burn, in contrast to paints and plastics. The famous London Underground station signs and maps are instantly recognisable uses of this unique product.
This article comes from iom3 edit released