Complex sentence: The master potters were responsible for shaping the greenware, thus resulting in dramatic variations in styles; however the surface decorations were added by the patients either in the form of designs painted on the surface or patterns carved into the damp clay.
Split into simpler sentences: The master potters were responsible for shaping the greenware, thus resulting in dramatic variations in styles. The surface decorations were added by the patients either in the form of designs painted on the surface or patterns carved into the damp clay.