Understand the cost savings and higher profitability that comes from knowing how to print halftones well.
1. Excessive dot gain, especially in dark shadows and highlights.
2. Unpredictable color shifts in simulated process and four-color process printing.
3. Tonal compression (the loss of small dots below 8% and merging of dots above 85%).
4. The need to use higher squeegee pressure to compensate for dot gain and poor printing consistency.
5. Continual art “adjustments” to modify halftones that gain too much on press.
The good news is that if you can fix your printer to create a quality dot under magnification, then you can avoid all five of these issues and many others not mentioned. (If you can’t, then you need to consider upgrading your imaging system.)
The key to achieving and, more importantly, maintaining the quality of your halftones is to establish a system to check them. If this one extra step saves a lot of film and screen revisions, then this alone will score a big win for your company.
So how does producing a high-quality dot on your positives save you money?
• When your printer is working correctly, you will use significantly less film and ink than shops that continually have issues with theirs.
• The added control of starting with a clean dot will allow you to print with the correct squeegee pressure, leading to fewer scrap shirts at the beginning and end of a longer print run because the prints won’t vary in quality.
• Screens will wash out easier, expose faster, and require less tweaking in order to maintain shadows and highlights. You won’t have to remake screens as often, saving labor and materials.
• You’ll have far less press downtime dealing with printed halftones that just don’t look right.
3. You’ll reduce costs by more closely inspecting your screens.
Once your printer or CTS system is working well and producing good-quality halftone dots, the next place is to look is screenmaking and screen exposure. By examining your screens carefully, you can catch additional flaws that will detract from your ability to recreate the halftone dots in the positive.
Three screenmaking steps are critical to successful halftone printing:
1. Inspect the mesh surface before coating the screen.
2. Check the emulsion surface before exposing the screen.
3. Look closely (under magnification) at the dots in the stencil after washing out the screen.
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