There are actually three different types of pulp produced at the Port Townsend mill. Long-fiber unbleached pulp is made from wood chips. Shorter-fiber unbleached pulp is made from sawdust. Both of these are produced using a kraft chemical pulping process. In addition, as much as 30% of the pulp stream is fiber from recycled cardboard, mechanically reconstituted from old corrugated containers (“OCC”).
The highest quality pulp produced is that made from wood chips. That is because the longer the fiber, the stronger the paper. Much of this pulp is sent to market as pulp bales to be turned into paper elsewhere, but most of it is used to make paper on site. It is blended with the sawdust pulp and the OCC pulp to make a stronger product than the shorter-fiber pulp would alone.