Xylography, an early form of wood engraving, was first seen in China in the 1st century. It is the oldest known engraving technique. The wood of a pear tree is cut with the grain. A sharp tool such as a chisel is used to create a relief for the ink to be laid in. This is called the blackline method . Bois de fil gave way to bois de bout . Box wood is favored instead. In this method, cubes are instead cut against the grain and then pasted together and polished smooth. Designs are executed in as a negative so that it will be correct in printing. A separate plate is used for each color. Wohlgemuth , his student Dürer, Laurens, Soulas , Chièze , Miro, Derain , Lorjou and others have used this technique.