Fines are chips that fall below a minimum standard. Fines that exceed the relatively small required percentage of the total chip supply create real problems for pulp mills, such as plugged digester screens, excess chemical absorption, increased load to the recovery boiler, loss of fiber yield, diminished product quality, excessive heat in the chip pile resulting in chip degradation and higher dirt count. Fines are generally used to make wood pellets for fuel.

When sizing chips, you typically have acceptable chips, fines which fall below acceptable chips, and overs which are larger than accepts.