Understand the cost savings and higher profitability that comes from knowing how to print halftones well.
Regarding mesh, the biggest thing is having a well-tensioned screen that is clean and free of ghost holes. De-hazing the mesh will save you money because you won’t waste time and materials coating and exposing a screen that will not hold details well, forcing you to start over with a different screen. If you don’t use retensionable frames, it’s a good idea to mark specific screens that you know are well tensioned for your detailed halftone work and keep them separate from the ones that are more worn.
The emulsion surface of the coated screen must be smooth and of the correct thickness with no smears, lines, or drips. If the screens aren’t coated well, you may have trouble washing out the small dots in the halftone after the screen has been exposed. Improper coating can also cause the screen to break down during printing, with ink pushing through areas of the screen where it isn’t supposed to be. If you catch these mistakes before continuing, you won’t need to replace screens later in the prepress process or, worse, after the job has begun.
After exposure and washout, make sure that you’re produced a high-quality stencil by inspecting the edge of the dots one final time with a loupe and making sure that the stencil hasn’t been under- or overexposed. If everything looks good, you’re ready to set up the presses.
4. You’ll improve your quality and reduce waste by using screen tests.
A simple step to improving your halftone printing on a consistent basis is to include a gradient strip of halftone just outside the printed image on all of the screens. Although this will require more work in taping off the screen, it can be an invaluable test for press approvals because you will know right away if you have a problem. If the test strip doesn’t look good, then you can’t expect the halftones in the actual image to look good either.
The savings from screen tests comes through using them consistently. Even the best printers will have a screen come out badly now and again. Screen tests allow you to catch these occasional blips before you begin printing shirts that will have to be scrapped. You can also do test prints during the run if you’re concerned the colors may be shifting to see exactly what is happening with dot gain.
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