There are three type of surface decoration which are under glaze decoration, in glaze decoration, and over glaze 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 glaze surface such as brushing a color stain on a glaze.
3/ Overglaze mean the decoration is applied on a fired glazed surface which usually are 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. Application should not be too thick, otherwise, it will flake off as dry out. Adding small amount of the base glaze or feldspar in color can improve bonding with the glaze and body if 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 nice contract.
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 leather hard ware. After the colored slip is getting a bit dry, a sharp knife is used to carve out the clay slip to expose the nature color of clay body which this technique is called Sgraffito. More complicate design can be done with multiple layer of colored slip. Sometime, engoble can still be used on bisque ware by adding extra bonding agents such as fluxes, it increase the adhesion with the body when fired.
Wax-resist or Latex A material that use for blocking the un-colored area which repels the applied stain, color slip or glaze. It can be applied directly on green ware, bisque ware or a glaze