The age-old art of enamelling probably stems from ancient Egypt where from around 2000 BC it served to embellish gold jewellery with colour.
It was originally used to set chips of glass into small metal cells and it was only later that heat began being used to melt the glass chips onto metals such as bronze.
Although initially created for jewellery, enamel was used in the Middle Ages for religious art, and then in the Renaissance its popularity increased for other types of object. The origin of the word enamel is not entirely clear, with some believing it to derive from the Old Frankonian word smalt while for others it came from the Medieval German schmelzen (meaning to smelt). The German word seems to fit better as enamel actually refers to a vitreous coating, with or without the addition of colouring or opacifying oxides, fused to ceramics or metal objects. From the chemical-mineralogical perspective enamel is characterized as a natural vitreous substance consisting of a mixture of silicates, potassium, silica, soda, red lead, quartz, feldspar, borax and phosphate minerals. The colour depends on the percentage of metal oxides added.
The fusion of these vitreous paints occurs at temperatures of between 600°C and 1400°C. The high processing temperature led this process to be known as fired enamel.
There are around 700 colours of enamel, although with layering techniques for different colours you can achieve infinite combinations.
However, this type of enamelling has always presented certain limitations and drawbacks:
● With metal enamelling, you must first make sure that the material is suitable and can withstand a temperature of at least 1400°C without disintegrating.
● The material must have good thermal expansion otherwise the enamel will begin to detach itself during the cooling phase.
● The piece to be enamelled must not have excess soldering on the parts to be enamelled as this may alter the colour of the enamel.
● Different colours require different firing temperatures.
● Soldered metal objects must withstand high temperatures.
● Once fired, the enamel must be sandpapered to obtain a smooth, homogenous effect, achieving a transparency that enables light to enhance the colours.
● The decorated piece is sensitive to knocks.
Towards the end of the 1980s, research in the field of chemicals created new resins and polymers that led to the introduction of cold enamelling to the decoration market.
This involves two component resins that, once polymerized, guarantee a finish for the decorated piece that is as good as traditional enamelling. This type of decoration has numerous advantages compared to its predecessor:
● Ability to decorate any type of synthetic or natural support.
● Drying at room temperature or low temperature (max 100°C).
● Infinite range of colours that can all be mixed together.
● Minimal preparation of the support to be decorated.
● Low cost, both of the equipment required for the decoration and the product itself.
● Decoration has good shock resistance.