ISO 5350-4:20 06规定了一种使用反射光进行仪器检查的方法，以0.02 mm2至3.0 mm2的物理面积范围内污垢斑点的等效黑色面积(EBA)来估计片状纸浆中的可见污垢和碎屑。使用ISO 5350-4:20 06中规定的算法，最大污垢尺寸限制为3.0 mm2。扩展到其他斑点尺寸（例如，物理面积大于3.0 mm2的斑点）可能需要改变设备、计算程序或两者，并且不在ISO 5350-4:20 06中。ISO 5350-4:20 06不能用于物理面积测量，因为它可能无法正确测量该测量模式的污垢斑点。 根据ISO 3688测定，待评价样品的亮度应为30%或更高。如果表面太粗糙或有纹理，可能需要将一些纸浆片材改造成实验室片材。 ISO 5350-4:20 06也适用于再生纸浆。

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.