This room houses 15 enormous mallets distributed in groups of 3. Each group crushes the contents of the stack. This is intersected by the ‘cam tree' which enables the whole mechanism to operate. The strips of material mixed with water pass into each of the 5 stacks one after another, undergoing a slow transformation. After 24 to 36 hours this processed is finished and a thick paste has been produced. To refine it, it goes into another kind of stack known as the ‘Hollander' because it was invented in Holland in the 18th century, and offers the advantage of bypassing the ‘rotting' process. The Hollander is an oval melting vat in which a cylinder covered with blades turns thereby shredding the thick paste for one and a half hours, whilst water continues to circulate. This invention is progress compared to the traditional mallet stack, since not only does it avoid the long process of ‘rotting' but it also produces a finer, smoother paper. Four mallet stacks are capable of striking 700 times a minute, whereas the ‘Hollander' can shred at between 50 and 100,000 cuts a minute. At Vallis Clausa both systems are used together.