When pottery became waterproof this was a major breakthrough. Man had been attempting to make clay less porous since ancient times. We know that glassing was carried out in Persia and Asia Minor as early as 3,000 years BC but it was brought to Spain by the Arabs and became of widespread use in the 10 th and 11 th centuries. White tin enamel has been used in the Basque Country since the 17 th century.

After the Spanish Civil War, and in view of the shortage of tin from England, Basque potters started to use a different whitening technique. Once the pieces were dry, they were bathed in a white clay paste to disguise the red colour of the clay and then glassed. This method was used up to the 60’s and 70’s when the few remaining traditional potters started to close down.