Using the shellac resist technique is a good way to create raised surfaces to delineate pattern and shapes on the surface of your object. It works by painting shellac onto the surface of a dry piece, then after the shellac has dried, you wipe the surface of the form with a damp sponge. Anywhere that has shellac on it will resist the water from the sponge and therefore stay raised on the surface in relation to the areas being wiped away by the sponge.

A couple critical aspects of this process are: 1) the clay body needs to be very smooth with no grog and 2) the work should be bone dry when you wipe the surface with the sponge.

The following video walks you through the process: