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3. Types of pottery

What is in a name? 

Earthenware - Low fired and porous, any color. 

Stoneware - High fired and not porous, often coarse, any color.

Porcelain - High fired and not porous, smooth, white, and translucent.

Porcelaneous-Stoneware - Potentially even stronger than porcelain and stoneware,  smooth, dense, any color, but often white, not translucent (to avoid excessive glassiness).

How are the pottery types different? How are they the same? 

Just like the common rocks of basalt or granite (or the Earth's crust generally), they all rely primarily on a high percentage of - that 'universal lego' -  Silica (50-75%) to give them their rocky/glassy character.

And, while variations in chemistry do effect properties like melting temperature, expansion with heat, color, etc., it is also instructive to note that; in a mix where the non clay part of the mix is well ground and dispersed, it is the degree of heating/melting that determines the major properties of porosity/density, strengthand glassiness.  

The name is often based on the temperature used to fire the dirt/silicates.

Indeed, with only one, carefully chosen, iron free,  composition, AND A PROGRESSIVELY HIGHER FIRING, it is possible to produce everything from a white  and porous earthenware, to a dense and white stoneware, to a translucent porcelain, and even a transparent glass - ALL WITH THE SAME MIX! 

Practically speaking though, other properties, like formability, melting temperature, color, texture, and coefficient of expansion, all become more important to the potter than having one mix that will work for something at all temperatures.   Ultimately the potter becomes very familiar with both manipulating the chemical balances, as well as the physical size, shape, and form of the - mostly silicate - particles that go into the starting mix.   

Remember though:  If it comes out of the ground, odds are it will have enough silica to get melted into a blob of glass - usually brown or black because of the abundance of iron oxide in the earths crust.