Completar Frases Wood 1Versión en línea Wood as a technical material (I) por Fernando Martínez 1 ring bark evergreen material hardwoods natural heartwood Hardwoods heavy Softwoods hardens centre Heartwood deciduous builders harder strength sapwood softwoods annual manufacturing Wood is a that has been used for many centuries by and craftspeople . There are two basic types of wood : hardwood and softwood . are generally than and come from trees . come from trees . They are not usually as as . Each year a new layer of growth is added just below the , producing an . New growth is called . New layers grow on the outside and the centre to form . is found at the of a tree and is the best part of a tree to use for , because of its hardness and .