Undesirable interference pattern in process printing.
Causes:
– Improper screen angles;
– Anilox screen count too similar to plate screen count.
Solutions:
– Screen angles of each colour should be 30° apart. The yellow should be 15° between colours, commonly the cyan and black;
– The nominal screen ruling must be placed 7.5° away from the anilox screen angle;
– Select an anilox screen count of a ratio of 5.5 to 1 i.e. 1001pi plate/550lpi anilox.
For example, a 165 line anilox used with a 85 line screen plate can cause moire because 85 x 2 = 170 which is too close to 165 line.
