English to Spanish Art/Literary Archaeology Ceramics

The following is a label next to a case in a museum of archeology, describing its contents:

"El Paso Polychrome
Unpolished, but flamboyant black and red designs painted over brown, unslipped clay; coarse temper; enormous jars; and strange shapes make this pottery type unlike any other found in the Mogollon region."


I've looked up what tempering means, and it refers to particles added to the clay so that it holds its shape, won't crack, will be less sticky and will withstand heat better. In those times the tempering agents that were most commonly used were crushed potsherds and burned and crushed animal bones and shells. I can't find the Spanish translation for this, help!