Glazing is almost as old as porcelain – the finest of all ceramics. Porcelain was invented in China during the Tang dynasty, and the earliest glazed objects come down from the 8th century. Requiring meticulous care, the details of the process of glazing are not known to the broad public.
The layer of glaze on the surface of porcelain objects is a 200-300 micron thick cover of glassy structure,” says head of the department of technology and product development Bernadett Kolláth. This glittering layer of glass adds to the porcelain’s aesthetic value, and it also has an influence on its mechanical tensility and resistance to chemical substances. In everyday use, the glaze layermakes the porcelain surface easy to clean, and serves as a fine base for ornamenting.
There are two methods for glazing: dipping and vaporisation. With the first firing, the objects reach the necessary firmness and porosity.
You should imagine them as a sponge-like, firm material with holes too tiny to see with the naked eye. The porosity resulting from the
small holes and narrow capillaries can be up to 35–40%, which makes the material suitable for absorbing the water content of the glaze, and by doing so, solidifying the glaze on the object’s surface.
Glazing Herend porcelain with pierced patterns or richly ornamented objects with small figures, bits and parts requires great expertise, and is done by hand just like moulding. It takes years of experience and meticulous attention to make the layer of glaze perfectly smooth, even and of the right thickness. The glaze’s glassy structure reaches its final shape in the second firing, at around 1400 °C.
There is a wide variety of glazes – offering an exciting and colourful choice. Most of the Herend Porcelain’s are covered with transparent glaze. Therefore, you can look at the translucent surface as if you were looking into a mirror. The silky, ivory colour, crystalline glaze is called matte glaze. Coloured glazes are suitable for presenting the exciting interplay of the surfaces ornamented with reliefs.
The time required for glazing depends on the complexity of the object. It may take up to 3–5 hours for pieces glazed by way of vaporisation. Some exquisite pieces may take several days to glaze. For example, glaze vaporisation and cleaning the Herend Ornamental Vase’s body takes a day, and preparing its base and lid takes another.
Source: Herend Herald – Written by: Fruzsina Szakály