TAPPI Standard Practice T 564 sp-11, “Transparent chart for the estimation of defect size,” is now available. This new 2011 Edition for the paper and pulp industry provides users with an editorially corrected standard practice on the use of the transparent chart itself.
There are many applications where it is desired to measure the size of spots, defects or inclusions in paper and other industrial materials such as textiles or plastics. The transparent chart was developed from the paper format “TAPPI Dirt Estimation Chart” to provide an additional means for size estimation.
The opaque TAPPI Dirt Estimation Chart is a photographic print of the original chart developed for use with TAPPI T 213 “Dirt in Pulp” and T 437 “Dirt in Paper and Paperboard.” The basis for these two tests is to determine the numerical or visual estimation of dirt in paper, paperboard, or pulp in terms of equivalent black area (EBA). EBA of a dirt speck is defined as the area of a round black spot on a white background on the Dirt Chart which makes the same visual impression on its background as does the dirt speck on the particular background in which it is embedded. Reflected light is the proper basis of comparison.
Only the TAPPI Dirt Estimation Chart, printed on the opaque, white background can properly be used in the tests. Photocopies, transparencies, plastic-covered cards, or printed reproductions of the chart (including the reproductions of the charts printed in the Test Methods for informational purposes) will not give equivalent results and must not be used in order to run the tests as specified in the Test Methods.
Over the years, a transparent version of the TAPPI Dirt Estimation Chart was produced by request from industry segments that wanted only to have a size estimation method for determining size of spots, defects, or inclusions in paper or other industrial materials such as textiles or plastics. In 1996, a method, T 564 “Transparent Chart for the Estimation of Defect Size,” was developed for use with a transparent version of the Dirt Chart. The transparent Size Estimation Chart (ordered and purchased separately from the TAPPI Test Method) should only be used as proscribed by the procedure described in T 564. The transparent chart has also been adopted for use with an International Standard, ISO 5350-3 “Pulps – Estimation of Dirt and Shives. Part 3 – Inspection by Reflected Light.”
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