Proto-Delft is an interesting group of Dutch earthenware that is the forerunner of Delftware. It is applied to the group of objects made in the transitional period between the exclusive manufacture of majolica and the early years of faience production (ca. 1629-1669).
The Dutch majolica potters were faced with competition after the arrival of Chinese porcelain on the Dutch market. Chinese porcelain was preferred over the Dutch product for its wider range of tablewares, and the thin and shiny surface inherent in the porcelain medium. As the demands for Chinese wares increased, the Dutch potters had to overcome both stylistic and technical challenges to imitate porcelain. These developments took place around 1620, with Haarlem and Delft playing leading roles in this process of innovation.
One of the problems that had to be overcome was the type of glazing. A characteristic of majolica is the use of both tin and lead glazes. A tin glaze results in a white, opaque surface, whereas a lead glaze was more cloudy and lacked the bright white color of the tin glaze. Since the tin glaze was relatively expensive, the potters often used the cheaper lead glaze on the underside of dishes. On the contrary, porcelain has a natural white color, and to imitate this, the potters had to cover the entire surface with the expensive tin glaze. After the initial firing, known as the biscuit firing, the object was completely dipped into tin glaze to make the whole piece appear white.
Another feature of majolica are the spur marks, which were created during the firing of the objects. As the objects were piled up on top of each other in the kilns, the potters placed little tripod stilts or cockspurs between them to prevent the pieces from sticking to each other. In the firing process these spurs usually became attached to the glaze and had to be broken away after the fire, which inevitably left three blemishes in the glaze and thus in the most visible part of the decoration. Since there were no such marks in Chinese porcelain, the potters had to find another way to fire the objects in the kilns. Instead of using spurs, they switched to an old Italian technique in which the painted plates were placed in cylindrical saggars with the help of ceramic pegs. These saggars were made of fireclay, able to withstand high temperatures, which protected the wares from ames and smoke in the wood-fired kilns. Each plate rested mostly on three ceramic pegs pushed through the wall of the saggar, which left only three minimal marks on the back of the rim. Finally, the inside of the saggar had to be saturated with undiluted lead glaze, and carefully sealed with clay to ensure that the component of the glaze which gives the shine could not evaporate during firing nor be absorbed by the saggar. Other advantages of the use of these saggars was the fact that the pieces were far less exposed to the dangers of falling soot and ash, and the temperature was more even. An example of these early wares that were fired in saggars is this blue and white plate, which is dated 1659. The center shows a conical form, which is probably a sugarloaf, flanked by the letters “A” and “I”. These letters possibly refer to Abraham and Isaac Pereira who started the first major Jewish sugar refinery in Amsterdam in the mid-seventeenth century. In 1656 they constructed two buildings at the Waterlooplein: a sugar factory at number 11 and a house at number 13. In 1658, the company started producing (under the name Thomas Rodrigues Pereira), and finished products were sold in 1664. Although it was a very lucrative industry, sugar was rare during the seventeenth century and was limited to the wealthy elite.
In addition to these technical improvements, the potters also changed their color palette and decorations. Delft potters began to produce wares in the style of the Chinese Kraak porcelain, and they also invented a more Western style of decoration. In contrast to the richly colored majolica wares, the objects were painted completely in white with blue decorations. The often elaborate decoration on the rim of majolica plates and dishes was replaced with a more sober decoration, or with an undecorated white border. The center was often painted with biblical scenes, and land or seascapes. Although the quality of the painting differs widely, the majority appears to be quickly and sometimes a little roughly painted. This blue and white biblical charger from circa 1660 shows the story of the liberation of Saint Peter. It depicts an angel rescuing Saint Peter with an aureole. The liberation of Saint Peter was a popular subject for several printmakers. In the print of Nicolaes Lastman (1585-1625) after a design of Jan Symonsz. Pynas (1582-1631), Saint Peter is taken by the hand of the angel, who leads him past the sleeping guards. It is highly probable that the earthenware painter was inspired by such prints. The types of prints available to the Delft artists in the the seventeenth century were woodcuts, etchings or engravings. These prints would be in the collection of the potteries, kept for this purpose, or supplied by a client for a special commission.
These technical innovations were not all made simultaneously and many objects can be categorized as proto-Delft because they have qualities of both majolica and faience. Some known objects resemble majolica, but were fired in saggars. The opposite is also possible: pieces that were fired according to the old method with spurs, but were tin-glazed all over or had a blue decoration. Interestingly, Van Dam refers to a majolica plate, which looks rather similar to the faience wares in decoration, but has the shape of a majolica plate, a standring, was fired on kilns and is covered on the reverse with a lead glaze: “Apparently one of the majolica potters tried to imitate the new faience already in 1633, without adapting in a technical sense. The majority of these pieces was probably made in Delft.”
 C. Wilcoxen, Dutch Trade and Ceramics in America in the Seventeenth Century, Albany Institute of History and Art, 1987, p. 54.
 F.T. Scholten, exh. cat. Dutch Majolica & Delftware, The Edwin van Drecht Collection, 1550-1700, The Hague (Paleis Lange Voorhout), 1993, p. 20.
 Scholten 1993 (note 2), p. 21.
 E.B. Schaap, Delft Ceramics at the Philadelphia Museum of Art, Philadelphia 2003, p. 17.
 J.D. van Dam, Delftse Porceleyne, Dutch Delftware 1620-1850, Zwolle/Amsterdam (Rijksmuseum), 2004, p. 14.
 Scholten 1993 (note 2), p. 21.
 J.D. van Dam, “Geleyersgoet en Hollants Porceleyn, Ontwikkelingen in de Nederlandse aardewerk-industrie 1560-1660” in Mededelingenblad Nederlandse Vereniging van Vrienden van de Ceramiek, 108, 1982/4, p. 61.
 Scholten 1993 (note 2), p. 22.
 Van Dam 1982 (note 7), p. 58.