The majority of flexographic printing plates are produced using a photo exposure process. Insufficient control of the plate processing parameters will lead to colour matching problems on the print. This investigation evaluated how the quantity of UV energy supplied to the plates during front and back exposure affect the geometry of halftone dots on the plate and how this subsequently affect the ink transfer to the substrate and the colour. Plates were produced using the range of exposure conditions used within the printing industry. These were characterised using white light interferometry to determine the geometry of the halftone dots and printed using an IGT F1 printability tester. The prints were measured using white light interferometry to examine the area and volume of the dots and a spectrophotometer to evaluate the colour. The effect of exposure was most significant on the shoulder angles of the dots. On the prints, the highlight and midtone regions were the most affected by the changes in the exposure resulting into tone gain increases of up to 10% at the lowest printing force considered which translated to colour differences of over 6 units (delta E_(1976)). The differences between the plates increased with increasing print force. Increasing the front exposure had the most significant effect on the shoulder angle of the dots on the plates and on the prints due to greater ink transfer from the shoulders of the dots.
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