Opacity paper testing

Transparent materials interact with light only by absorption. This interaction is formulated quantitatively in the Bouguer-Lambert and Beer s Laws (c.f. i). In paper, however, surface reflection is the dominating type of interaction. This results in very desirable properties like high brightness and opacity, but complicates the interpretation of optical tests with regard to absorption data. The Kubelka-Munk theory attempts to separate the two types of... 

Laslo, D and Bakke, E., 1984, Limestone/Adipic Acid FGD and Stack Opacity Reduction, Pilot Plant Tests at Big Rivers Electric Corp, paper presented at the 77th Annual Meeting of the APCA, San Francisco, CA, June 25. 

The determination of atmospheric dust spot efficiency is a staining test, described in detail in BS EN 779, and used for AC and ventilation filters. It is based on the intensity of staining of a target ultrafine filter paper caused by the flow through it of a quantity of dusty air. The intensity of staining is measured by an opacity meter, and provides an empirical measurement of the concentration of contaminant in the air stream. In the filter test, the downstream air flows constantly through its collection paper, while the upstream air is sampled for only a proportion of the time (because of its much higher dust concentration), and this proportion is controlled to yield an equivalent stain to that from the downstream flow. The flow ratio can then be converted to a filtration efficiency. 

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