The modern delft of to-day is not to be confused with the old Dutch delft. The Dutch ware made to-day which passes with the old name is a glazed ware and not, like the old, an enameled ware. In modern so-called delft one can see through the glaze. As I have said, old Dutch delft presents a completely opaque surface.
Just here I should say that in some of the later sorts of old Dutch delft a glaze was added to the enameled surface, but as the enameled coating is there, one will readily recognize it beneath the glaze. As the clay base of old Dutch delft was so soft and friable, the surface of a piece was entirely coated with the tin-enamel. While it was not metallic in the sense of having a metallic lustre like the maiolica of Deruta or of Gubbio, light glinted across the surface of a piece of old delft reveals a tinny sheen. The surface will prove smooth to the touch, but it will not feel glassy as does that of a glazed ware.
So friable is old delft that it is prone to crip at the edges, there revealing the brown body base of the under clay. A drop of strong acid dropped on the body clay thus exposed will effervesce, since there is carbonate of lime in the understructure of old delft. This body clay is so soft that it is easily cut with a knife. This cannot be said of the English Lambeth delft, which English ware, though inspired by the old Dutch delft and contemporary with much of it, was of a much harder body base, denser and more glossy than the Dutch clay. The enamel lay much more closely and evenly to the body base in old Dutch delft than it did in the English delft.
Dutch delft rarely crazed in the kiln; English delft often did so and in consequence its enameled surface came to be glazed to prevent this.
Then one often finds the colors of the decoration of old Dutch delft to have run—neither under nor over the enamel surface but into the enamel. This is because the colors were put upon the Dutch delft while the enamel was still wet and fixed in it during the liquefaction and fixing of the surface coating in the firing of the piece in the kiln. In such pieces of English delft as show the colors of their decoration to have run, it will be seen distinctly that these colors have run upon the enamel of the surface and not into or with it.
Finally the color of the clay body of the Lambeth delft of England is buff.
While nature has given us a sense of blue skies, scientists will tell you that she has been overly sparing with blue in flowers and in bird life. The Chinese had long placed this color as the first of the five nominated in their popular traditions. To blue they gave a symbolism rich and varied. They associated it with the East, for instance, and again with wood. It is natural that it should have been a favorite color for the Chinese ceramicist. The palace china of some of the early Chinese emperors reserved the privilege of blue decoration, a blue, as an old Chinese writer tells us, as “seen through a rift in the clouds after rain.” It was not until the sixteenth century that the Chinese obtained cobalt. This bright and vivid blue made speedy headway as against the grayer blues that until then had alone been produced by the Chinese ceramic artist. Cobalt was introduced into China by either the Jesuits or the Mohammedans; the Chinese themselves named the color “Moslem Blue.”
The blue-and-white porcelain of China appears to have made a direct appeal to the Dutch potters. Blue was the earliest color used by them in their delft decoration. Purple followed, and after that the green, yellow, brown, and red of the polychrome delft pieces that we know.
We do know how popular the Dutch blue-and-white became. Every year quantities of it found their way to England. Much of it was sold there at the Dutch Fair held annually in Yarmouth. King Charles II soon came to fear the effect on local potteries of the extended importation of Dutch delft into England and in consequence issued a proclamation against this commerce, declaring the sale of Dutch delft in England to be “to the great discouragement of so useful a manufacture so late found out” at home, presumably by the potters of Lambeth, who naturally would not be slow in attempting to imitate the Dutch ware so flourishingly in vogue. Probably Dutch potters had come over to work in the English ateliers. In the British Museum are interesting examples of English delft, a particularly fine set of plates having a line of poetry on each, so that when the six are arranged in proper order they form a little five-line verse.