In gerneral, there are three types of surface decoration which are underglaze decoration, in glaze decoration, and overglaze decoration.
1/ Underglaze decoration means the decoration such as painting or color is applied under the glaze coating.
2/ In glaze decoration means the decoration is in a glazed surface such as brushing a color stain on a glazed surface.
3/ Overglaze means the decoration is applied on a fired glazed surface which usually is lower temperature pigment such as China Paint or decal.
Painting with Color stain or Oxides - Color stain can be applied directly on leather hard, dried clay, bisque ware, or even a glaze just like watercolor. The application should not be too thick, otherwise, it will flake off as dry out. Adding a small amount of the base glaze or feldspar in color can improve bonding with the glaze and body if the application on a dry state. Generally, brushing decoration with oxides or stain is better on a glaze. Otherwise, the decoration on bisque ware might cause smudges if glazing uneven. Oxides in the incised area actually create a nice contrast.
Colored Slip or Engobe - The slip is a mix of colored stain with liquid clay(better with the same body clay. It is usually brushed directly on the leather hard stage. After the colored slip is getting a bit dry, a sharp knife is used to carve out the clay slip to expose the natural color of clay body which this technique is called Sgraffito. A more complicated design can be done with multiple layers of colored slip. Sometimes, engobe can still be used on bisque ware by adding extra bonding agents such as fluxes, it increases the adhesion with the body when fired.
Wax-resist or Latex - A material that uses for blocking the un-colored area which repels the applied stain, color slip, or glaze. It can be applied directly on greenware, bisque ware or a glaze.