glasiation

Glasiation is a term that appears occasionally in reference to the glazing of ceramic wares, describing the process of applying a glaze and forming a glassy surface after firing. In modern usage, glazing is the standard term, and glasiation is considered uncommon, archaic, or regionally specific. In some contexts, glasiation may be encountered as a mis-spelling or umbrella term for glaze-related work, rather than a distinct scientific concept.

In ceramics, glazing involves coating a ceramic object with a glassy layer. A glaze typically comprises silica as the glass former, fluxes to lower the melting temperature, and stabilizers such as alumina, with colorants added to achieve decorative effects. The glaze is applied as a slurry or paste, dried, and then fired in a kiln. During firing, the glaze melts and fuses to the underlying ceramic body to form a continuous, glass-like surface that is usually waterproof and often shiny. The final appearance and properties depend on the glaze formulation, the firing temperature and atmosphere, and the thickness of the applied coating. Improper combinations can lead to defects such as crazing, pinholing, or running.

Geology does not recognize glasiation as a distinct scientific term; it should not be confused with glaciation, the well-established process related to the growth and retreat of glaciers.

See also: glaze, glazing, vitrification, glaciation.