What is the difference between the opaque TAPPI Dirt Chart and the transparent TAPPI Dirt Chart?

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 ... more.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.