A group of aresta tiles placed on the altar located on the right side of the Palatine Chapel at the National Palace of Sintra.
In the late 15th century, a new process for separating colours was introduced into Spain. This was known as the “aresta” or “cuenca” technique, which involved the use of wooden moulds with grooves forming patterns that were stamped under pressure onto the clay tiles while still wet. The ridges that resulted from this procedure formed barriers that divided up the different areas of the tile to be filled with enamels and thus prevented the different colours from becoming mixed together. The corda-seca technique – which was the main one used at the National Palace of Sintra – and the aresta technique coexisted for the first few decades of the 16th century, reproducing the same decorative patterns of geometrical motifs, which later evolved into Renaissance motifs, as in this present case.