Burning out occurs when a substance in a product being fired has a lower burning point than what it is being fired with and burns away. This can be damaging or used constructively.
In the design shown in the photo below the outlines were painted with varnish on to tiles in the bisque state. Each space was then filled up with a color. The lines help to keep the colors separate and when fired the varnish burns away leaving the color of the bisque.
Products like vegetable oil, varnish and glues are used to fix colors on to a base that has already been glaze fired and they act as a binder during decorating.
Rice, petals, etc., can be put with clay or glazes to form patterns once fired. When fired they burn away leaving their shape indented. Read more about: Dry Cord