From about 1670, when Moronobu began to issue single-sheet prints, until about 1742, a period of at least seventy years, the prints were in black outline and were coloured by hand. They were, in fact, cheap paintings. Early in the eighteenth century the chief pigment used in colouring them was red lead. The Japanese name for this pigment is tan, and the prints upon which it appears are designated as tan-yé. About 1710 yellow and citrine were commonly used with the tan. Four or five years later a new style of hand-colouring, said to have been devised by Torii Kiyonobu, came into vogue and greatly modified the style in which the prints were designed. In place of tan he substituted beni, a very beautiful but fugitive red extracted from the saffron. This was used in combination with a greenish yellow (probably gamboge) and low-toned blues and purples. Finer details were introduced into the designs, and the colouring in general was more carefully done. In response to a growing demand for less expensive pieces smaller prints (hoso-yé) became common. To give brilliance to the pigments a little thin lacquer (urushi) was mixed with them, and, while wet, parts of the design were sprinkled with metallic powder, which was probably applied by blowing it through a small bamboo tube. These prints were known as urushi-yé, or lacquer prints. A little later the custom grew up of painting parts of the prints with black lacquer. Not until the year 1742 did the practice begin of applying colour by impressions from flat wood blocks. Why the invention should have been so long delayed, and why, after it was once made, nearly fourteen years more should have elapsed before the number of colour-blocks was increased beyond two, are questions to which no certain answer is yet forthcoming. It is incredible that during the forty years when innumerable hand-coloured prints were issued no one should have conceived the idea of printing the colour as well as the black outline. Without doubt some practical difficulty connected with the printing stood in the way. Possibly the thing that awaited discovery was the trick of mixing rice paste with the colour to keep it from running. Or, as is more likely, it took a long while to discover a practical method of securing accurate register in impressions made upon damp paper which was liable to stretch or shrink during the printing process. Whatever the problem may have been, the honour of the solution is due to Okumura Masanobu. Being a publisher as well as an artist, he was no doubt alive to the economic advantage of a cheaper process and to the attraction of novelty. Some years earlier he had invented the hashira-yé, or pillar-print, and had also put forth a series of prints that show a fair understanding of the laws of linear perspective to which he gave the name of Ukiyé. Being an artist as well as a publisher, Masanobu perceived that the change in process called for a change in the style of the designs.