PAPTAC - D.35
EQUIVALENT BLACK AREA (EBA) OF VISIBLE DIRT IN PULP, PAPER AND PAPERBOARD BY IMAGE ANALYSIS
|Publication Date:||1 February 2012|
This method uses 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 metre of sample. Using the algorithm prescribed in this method, 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 this test method. This method cannot be used for physical area measurements since it does not correctly measure the dirt specks for that mode of measurement.
The specimen to be evaluated must have a brightness, as determined by PAPTAC Standard E.1, "Brightness of Pulp, Paper, and Paperboard", of 30% or greater. It may be necessary to reform some pulp sheets into handsheets if the surface is too rough or textured.
This method is an instrumental equivalent of PAPTAC Standard D.36P, "Dirt in Paper" which reports the equivalent black area of dirt in parts per million.
This method can be implemented using any image analysis system, provided that it meets the criteria specified herein. Method D.36P uses the same definition of EBA and dirt estimation chart as described in TAPPI Test Method T437.
Measure all Ry value reflectances mentioned in this method according to PAPTAC Standard E.5, "Pulp, Paper and Paperboard - Colour Measurement with a Diffuse/Zero Geometry Tristimulus Reflectometer".