Kaolinite, feldspar and quartz (or other forms of silica) continue to constitute the basic ingredients for most continental European hard-paste porcelains.
Soft-paste porcelains date back from the early attempts by European potters to replicate Chinese porcelain by using mixtures of clay and frit.
As these early formulations suffered from high pyroplastic deformation, or slumping in the kiln at high temperatures, they were uneconomic to produce and of low quality.
Formulations were later developed based on kaolin with quartz, feldspars, nepheline syenite or other feldspathic rocks.
Biscuit porcelain is unglazed porcelain treated as a finished product, mostly for figures and sculpture.