There are two types of painting in the process of porcelain production: Underglaze painting and overglaze painting.
Underglaze painting means painting onto the bisque with a pigment before being glazed. The glaze protects the design, making it durable, but the high heat during the subsequent firing means only a limited color palette can be used, such as the popular sometsuke (blue and white painting).
Overglaze painting is made after the item has been glazed and glost fired. The lower firing temperature means that a wider color palette can be used compared to underglaze items.