A round dot is symmetrical, with no horizontal or vertical orientation. In offset printing, the common use of non-symmetrical (elliptical) dots facilitates the practice of using angle sets that separate the dominant colors of cyan, magenta, and black by 60°, instead of 30°. Maximizing the angle separation between rows of elliptical dots reduces potential moiré.
The standard use of a round dot in flexo makes 60° separation unnecessary. A round dot is symmetrical, which means that when it is rotated 90° it remains in exactly the same orientation. For this reason, shifted 7.5° angle sets only require 30° of separation. This means that all flexo angles combinations can be achieved using only one 90° quadrant. Again, a typical flexo angle set might be CMYK 67.5°–7.5° –82.5°–37.5°.
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