This method supplements TAPPI T 213 "Dirt in Pulp," which measures dirt in mm²/m² (parts per million) as
detected by reflected light by measuring dirt in actual dirt specks (above a given threshold value) as observed by
transmitted light. This method is most often used on slush pulps, whereas T 213 is more often used on dry sheets.
Either method, however, may be used with either type of pulp.
