Nickel Oxide is most often used to modify and soften the colour of other metallic oxides. Small amounts are normally all that is required. Nickel oxide is normally used in High fire glazes due to the refractory nature of nickel oxide powder. Glazes that are already matte or immature will be made drier by the addition of nickel.
A grey-green material which produces a grey colour in lead glazes and brown in glazes containing barium; in the presence of calcium the colour is tan and in high magnesium glazes a bright green. With small quantities of zinc, a steel blue develops, while with larger quantities it is lavender blue, when in stoneware glazes under reduction. Nickel is most often used to modify other colours (up to 5%)