Description
99% red iron oxide. This coarser grade produces fine specks in glazes compared to Iron Oxide Fine No. 421
In glazes: Iron oxide is the most commonly used oxide in ceramics, both as a flux and as a colourant. It lowers the melting point. At additions of 1-8%, it produces colours ranging from honey yellow to dark brown. In alkaline glazes it produces colours ranging from red to violet; under reduction firing conditions, it produces grey-green to bluish tones (celadon). An alkaline glaze supersaturated with iron forms crystals (aventurine).
In clay bodies: Iron affects the fired colour of the ceramic body. It is reddish brown and, when finely dispersed, colours the body the same shade. If lime is present, the colour changes to yellow. It is present in all bodies that fire yellow-brown to red.
In engobes: Adding 5-10% iron oxide to a white engobe produces a reddish-brown engobe.
