This series was printed on two different types of paper - "Line binding" 和 "Twill binding".
Line binding produces a paper weave that is a cross pattern of horizontal and vertical lines and will look like a checkerboard pattern when a light is shown through the paper.
Twill binding produces a paper weave that is diagonal in orientation, that is if you pass light through the stamp you should see a light diagonal pattern in how the paper was laid in the paper press.
This series was also printed with two different number of dots per square cm, 90 and 80. The difference is sometimes hard to determine. It can be detected by the "fineness" of the printing - a 90 dots raster will look "sharper" than an 80 raster, since the image is composed of more closely placed smaller dots of color.
This stamp was printed on Twill binding paper with 90 dots per square cm.
