One of the best clays in the Basque Country for making cooking vessels was that used in Zubitza (Navarre), although casseroles and stewpots were also made for this purpose using clay from close to the potteries of Irunberri, Lizarra, Marañon, etc. In Gipuzkoa, Alava and Bizkaia-and very probably in the French Basque Country-because good local heatproof clays were not available, such vessels were largely imported from Muelas del Pan and Pereruela, in the province of Zamora.
Madoz's "dictionary" (1850) says of Muelas del Pan:
Industry and Commerce: Construction of clay vessels, which are sold to the Basque Provinces and even on occasions to France.
L. L. Short, in Zephyrus, No. 2-3 (Salamanca) says of Pereruela:
Usually, the potter sells the vessels on to retailers and does not sell directly outside Zamora. These Zamoran retailers take the products from Pereruela to Galicia, the Basque Country, La Montaña, Burgos and sometimes to Andalucía.
In the 1970s we spoke to José Martínez and Domingo Blanco in Muelas del Pan. They had both sold stoneware and remembered often sending vessels to potters in the Basque Country, including Sabino Ortiz de Zárate (Elosu), Miguel Arretxaga (Durango), Leandro Ganzabal (Ametzaga), Fructuoso Fernández de Larrinea (Elosu), etc.
The vessels were brought from Muelas del Pan as bisque-in other words they were fired but unglazed. The Basque potteries enamelled and re-fired them.
Our source in this town knew of more than a hundred female potters. The women made the vessels using very primitive wheels, turned by hand when firing.
It was the men who extracted the soil, prepared the clay, fired the vessels once they had been cast and sold them. This wheel was very similar to that used in Pereruela, Moveros (Zamora), Poyastruc, Ordizia, etc.
But although most cooking vessels came from these two towns, they also brought them from the towns of Errabal del Portillo and Las Navas del Rey in Valladolid. These vessels were generally glazed on the outside and enamelled on the inside.