Burnished and polished foot of a four-footed aquamanile (ewer) dating from around 1300. 

Burnishing involves compacting the surface of a leather-hard vessel by applying pressure using a smooth implement. Areas that have been burnished differ from non-burnished areas by the fact that they are shiny or even slightly reflective and this effect can also be used to create patterns. By the modern era, burnishing as a decorative technique had become practically outmoded in Swiss ceramic production.

Translation Sandy Haemmerle

German: Glättung

French:  tesson poli