to fiber length in a bauer mcnett fractionator the 16 30 mesh fraction i e fibers which have passed through the 16 mesh screen but are retained on the 30 mesh screen contains neither shives nor fines shives are retained by 16 mesh while fines pass through 30 mesh the tensile index of this fraction which in the test comprised about 15 of the whole sample is considered to be a good measure of how well developed the fibers are the observed tensile index values which are shown in table 7 below clearly show that the whole sample as well as the 16 30 and the 50 200 mesh fractions from the apex stream were of inferior quality as compared to those of the base stream it is therefore obvious that the strength difference between the base and apex streams is not caused by differences in the amount or the quality of the fines tmp for newsprint was fractionated in a laboratory test in order to determine the amount of fibers with low bonding ability in the pulp and therewith the need of fractionation and size of subsequent refining equipment the fractionation was carried out in three stages in accordance with fig6 the hydrocyclones used were of the same type as the hydrocyclones c described.