Chapter 12 
Figure 2 
The color-matching technique scale shown on a cigarette package. (Pantone- 
colored papers representing low, standard, and high yields at scale locations 2, 5, 
and 8, respectively.) The appearance of an unblocked vented filter is shown in the 
bull's-eye stain; the uniform stain on the filter end indicates extreme vent blocking. 
1 L 
1 
1 1 
1 
1 1 
■ 
1 
1 ^ 
1 1 
0 1 2 3 4 5 6 7. 
Low Medium i 
B 
Higt 
9 10 
1 
To use scale, filter must look 
like (^, not O 
Not 
Necessarily 
Lights 
darker, or about the same as each of the colored blocks, and then selected 
the most appropriate scale number" (Kozlowski et al., 1982b). 
Figure 2 also shows how stain patterns on spent filters can be used to 
indicate whether vent blocking has taken place on a conventional ventilated 
filter cigarette (Kozlowski et al., 1980). The bull's-eye tar stain on the left 
indicates no vent blocking. (Diluting air rather than smoke has been drawn 
through the periphery of the filter.) The uniform tar stain on the right 
indicates extreme vent blocking. On ventilated-filter cigarettes, vent 
blocking decreases filter efficiency so that the amount of stain left in the 
filter underestimates the amount of smoke that has gone through the filter; 
167 
