Screen dots are (not) visible
Ink
Problem
1. Too thick.
2. Too thin.
Solution
1. Thick ink with fast thinner produces visible screen dots.
2. Thin ink with slow thinner (retarder) causes invisible screen dots.
Cliche
Problem
1. Etching too deep.
2. Wrong screen ruling.
3. Wrong cliche type.
Solution
1. Produce new cliche with shallower etching depth.
2. Depending on results desired, use finer screen for invisible screen dots or coarser screen for visible screen dots.
3. Use cliche type suited to screen type.
Pad
Problem
1. Surface too rough.
2. Wrong pad shape.
Solution
1. Replace pad.
2. Depending on results desired, use more tapered pad for visible screen dots or flatter pad for invisible screen dots.
Substrate
Problem
1. Surface too coarse/ very structured.
Solution
1. In this case, not the screen dots are visible, but the surface structure.
Other
Problem
1. Poor quality of artwork.
Solution
1. Check screen dot pattern on film or expose in new screen.
Screen dots are desirable for some prints, but not for others. Some photopolymer cliches cannot be produced
without a screen, or only with a certain type of screen. With steel cliches, the screen is only exposed in for
support of the doctor blade, to allow printing of larger motifs over an entire surface.
