Having examined the collection and processing of recyclable materials, we will now consider the third stage of recycling, that of material reprocessing. The key characteristic of this stage is that the form of the recyclable material is changed. In the first two stages of recycling such material is merely handled, but in this final stage there is a physical change in the form of the material to produce a recycled material. Thus, paper is repulped, glass and metals are remelted and plastics are granulated and may be re-extruded. In all cases the materials are cleaned and contraries removed.