Industrial porcelain enamel

[1] It is most commonly used in the production of cookware, home appliances, bathroom fixtures, water heaters, and scientific laboratory equipment.

[3] Mild steel is used in almost every industry and a huge array of products; porcelain enamel is a very economic way of protecting this, and other chemically vulnerable materials, from corrosion.

Being a fired ceramic, porcelain enamel is also highly heat-resistant; this allows it to be used in high-temperature applications where an organic anti-corrosion coating or galvanization may be impractical or even dangerous (see Metal fume fever).

[3] Porcelain enamel is used most often in the manufacture of products that will be expected to come under regular chemical attack or high heat such as cookware, burners, and laboratory equipment.

In recent years, agricultural silos have also been constructed with porcelain enamelled steel plates to protect the interior from corrosion and the exterior from weathering; this may indicate a future trend of coating all outdoor mild steel products in a weather-resistant porcelain enamel.

Most modern applications also involve two layers of enamel: a ground-coat to bond to the substrate and a cover-coat to provide the desired external properties.

The most important processes are the cleaning of the surface of the substrate; all remnants of chemicals, rusts, oils, and other contaminants must be completely removed.

To facilitate this, frequent processes performed on substrates are degreasing, pickling (which can also etch the surface and provide anchoring points for the enamel), alkaline neutralization, and rinsing.

This method requires a high level of operator skill and concentration to achieve an even coating, and due to its inconstant nature is not often used in industrial applications.

[15] Firing, where coated substrates are passed through a furnace to experience long periods of stable high temperatures, converts the adhering particles of frit into a continuous glass layer.

[16] Porcelain enamel has been applied to jewelry metals such as gold, silver, and copper since antiquity for the purposes of decoration.

It was not until the Industrial Revolution that ferrous metals first became the subject of porcelain enamelling processes; these first attempts were met with limited success.