Corefining of the black spruce chips with xerographic recovered paper
was conducted using a chemithermomechanical pulping (CTMP) process. Re
placing 15% of wood chips by recovered paper in the form of small shee
ts in a CTMP with 3% Na2SO3 resulted in substantial improvements in st
rength properties and a small reduction in optical properties when com
pared to the 100%-chip CTMP counterpart. There was no apparent adverse
effect on fiber length, and no excessive fines were observed in this
study. The results of this exploratory work indicated that there may b
e practical application of the corefining technique for producing news
print furnishes. However, further studies are needed to better underst
and the corefining mechanism.