A glaze is a layer of glass with which a fired clay product can be covered. The glass is composed of a mixture of non-organic minerals: metal oxides and silicates. This is mixed with water to form a liquid, which is then poured over a ceramic product, or else the product is immersed in it or sprayed with it. When the product is fired with the glaze, the powder mixture melts to form a solid glass layer that adheres to the fired clay to which it is applied. The properties of a glaze can vary enormously. Ranging from a predictable colour and gloss to a less predictable character in which rich nuances of colour, gloss and effects can occur. It is mainly this last category that is increasingly recognised as a rich and natural skin for a ceramic element or building.