Fritware is the crow-bar method of making porcelain at super low temperatures. Frits are used where much higher material costs can be accepted to produce a body that fires glassy, white, at a very low temperature and rapid rate-of-rise.
Traditional porcelains are made from feldspar, clay and quartz and fire above 2200F (1065C). Typically around 20-30% quartz is needed for glaze fit and 25-35% feldspar for maturity. The remainder is the whitest and most plastic clays available or justifiable for the cost. Plastic fritware bodies are most easily made by simply replacing the feldspar with a high sodium frit. Near zero porosity can be achieved around cone 04-03. However if more frit that can be tolerated even lower maturing temperatures are possible (to an extreme where more more than 90% is frit and the body is vitreous at cone 020.
Fritware at Wikipedia
A ceramic whose priorities are translucency, whiteness, fired strength and resistance to thermal shock failure.