scope:

1.1 This test method covers the use of image analysis to determine the level of dirt in pulp, paper, and paperboard in terms of Equivalent Black Area (EBA) of dirt specks within the physical area range of 0.02 to 3.0 mm² reported in parts per million as well as the number of dirt specks per square meter of sample. Using the algorithm prescribed in this test method, the maximum dirt size is limited to 3.0 mm². Extention to other speck sizes (for example those greater than 3.0 mm ² in physical area), may require changes in equipment, calculation procedures, or both, and is not covered in this test method. This test method cannot be used for physical area measurements since it does not correctly measure the dirt specks for that mode of measurement.

1.2 The specimen to be evaluated must have a brightness, as determined by Test Method D 985, of 30 % or greater. It may be necessary to reform some pulp sheets into handsheets if the surface is too rough or textured.

1.3 This test method is an instrumental equivalent of Test Method D 2019, TAPPI T 437, and TAPPI T 213, all three of which report the equivalent black area of dirt in parts per million, and TAPPI T 537, which reports the number of specks of 0.02 mm² or larger per square meter. This test method can be implemented using any image analysis system, provided that it meets the criteria specified herein.