Making Pulp from Wood
This is a very cost effective but energy
intensive process. because all the log apart
from the bark is used. The log is put through a grinding or refining process to
separate the fibres. Chemicals are not used, but there is a high energy use
which can only partly be offset by using the bark as fuel. Mechanical pulp
retains all the natural tree substances - sap, sulphur compounds, sugar and a
lignin which binds the fibres together. Because lignin reacts with ultra violet
light, papers made from mechanical pulp tend to 'yellow' when exposed to light.
Mechanical pulps are used to manufacture
newsprint and some packaging boards.