Breather #5

To the bone

Ever wondered what were the common elements between a teapot, a pasture and a leather shoe ? What ? Never wondered about that ? How peculiar !

Yet, the answer is simple : a cow. The soft-eyed, placid and mooing kind. This guy. Or girl. It’s hard to tell without its business card.

Baffled are we ?

And yet it’s true.

One of the most prestigious and onerous kind of soft-paste porcelain contains at least 30 % cow bone ash. It’s called « Bone china ».

Add a dollop of kaolin, a dash of feldspar, a sprinkle of quartz, a spoonful of mica and a little water  to it and there you have it : a blinding white, strong, resistant and translucent pottery paste able to rivalize with the most refined Chinese porcelains without the hassle of the trip.
For the pottery geeks among you, dear readers, bone ash is composed of calcium oxide and phosphorus pentoxide. In a nutshell, bone ash acts as a flux to lower the other compounds fusion temperature and allow their liquefaction to create glass-like results.

Thomas Frye (1710-1762) was the first known to industrially develop an ash bone based paste in the Bow Porcelain Factory near London.

Bow porcelain factory Vase, V&A collection. Click the image to know more.

Then, the paste was further more refined by Josiah Spode (1733-1797) in Stoke-on-Trent where it acquired both the stability and refinement that is known today but also where it emanated throughout Europe before other manufacturers took hold of the formula’s principles.

During the first half of the XXth century, bone china or « English porcelain » was one of the must-haves of every wedding lists, though its price was -and remains- high.

Doulton factory bone porcelain Jug, V&A collection. Click the image to know more.