Abstract: The decorations (6) made by the apparatus are realized by the use of solid particles (7) in the form of scales, sands or granules, which are deposited on and adhere to the hot tarred surface of the membrane (1). The apparatus includes at least one device for applying solid particles (formed by a rotating roller (10) or a rotating ring-wound continuous belt (14-17)or a rotatable plate (19)) provided with shapes (8) having a same shape as the final decorations (6) on the membrane (1) will have. The solid particles applying device is associated to a hopper (9) containing the solid particles (7) in such a way that the particles (7) fall by force of gravity from the outlet mouth of the hopper (9) onto the solid particles applying device and thence from the shapes (8) cut into the solid particles applying device onto the transiting membrane (1), forming the decorations (6) on the membrane (1).