There’s an interesting Aug. 23, 2012 essay by Will Soutter for Azonano about colloidal clay and some early nanotechnology products,

… colloid chemistry, which deals with the chemical and physical interactions of nanoscale particles, is a much older field – it has been studied and used in the chemical industry extensively since the early 19th century.

Even before colloids, or nanoparticles, were fully understood, they were used in many manufacturing techniques, to produce glass and ceramics with unusual, attractive properties.

I have come across reference to nanoparticles and glass (my Sept. 21, 2010 posting about the Lycurgus Cup) but this is the first I’ve heard of clay and nanoparticles,

Porcelain, which is a much finer-grained ceramic, does not require glazing – it is inherently waterproof, and has a more attractive appearance. These properties stem from the main constituent of the clay used for porcelain, called kaolinite, or china clay.

The colloids in this clay are extremely small, and behave differently to other clay particles when in solution. The particles, like most clay colloids, are platelet-shaped and have negatively-charged flat sections. Unlike most clay particles, however, they also have positively charged edges, which changes the colloid dynamics almost entirely and results in a different solid structure when the porcelain is fired.

The article is illustrated with images of porcelain and ruby glass demonstrating the effect that nanoparticles can have on materials.