ISO 5350-4:2006 specifies a method using instrumental inspection by reflected light for the estimation of visible dirt and shives in pulp manufactured in sheets, in terms of Equivalent Black Area (EBA) of dirt specks within the physical area range of 0,02 mm2 to 3,0 mm2. Using the algorithm prescribed in ISO 5350-4:2006, the maximum dirt size is limited to 3,0 mm2. Extension to other speck sizes (for example, those greater than 3,0 mm2 in physical area) may require changes in equipment, calculation procedures, or both, and is not covered in ISO 5350-4:2006. ISO 5350-4:2006 cannot be used for physical area measurements since it may not correctly measure the dirt specks for that mode of measurement. The specimen to be evaluated should have a brightness, as determined by ISO 3688, of 30 % or greater. It may be necessary to reform some pulp sheets into laboratory sheets, if the surface is too rough or textured.ISO 5350-4:2006 is also intended for recycled pulp.