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The Value of Standards in Printing Halftone Blends

(June 2009) posted on Fri Jun 12, 2009

Garment designs that feature blends tend to attract more attention than plain decorations. Trimingham explains how to develop standards for applying blends in your printing operation.

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By Thomas Trimingham

Start with the most printable dot for your shop when testing inks for blending. Finding this dot is accomplished by creating a test pattern of assorted resolutions (measured in dots/in.), which is then output as a positive your best film, exposed, and printed through the higher mesh counts reserved for halftone printing (Figure 1) on garments. Typically, this is a 200- to 390-thread/in. mesh count.

Evaluate your test print and identify the halftone line count that prints with the best tonal range. Careful inspection is required to see the best test strip—the one that maintains a clear 0-100 set of steps. If you have trouble finding the division between the 80-90-100% tonal ranges on the printed strips, tonal compression is to blame and a bigger dot will likely solve the problem. Also keep in mind that a lot of tonal compression in this test is a sure-fire sign of printing with too much pressure. Remember, it is critical that you perform this test with everything in the same process as the final job and with the same pressure levels, which as stated earlier, should be as low as possible. Also, using extra flashes or other production steps will only cheat you out of the results that show what you need to do to prevent problems in production.

Run a couple of blending tests after you’ve identified the ideal halftone line count. You might be thinking, “I don’t have time for all of these tests.” While I understand the urgency of making money by keeping presses running with production orders, it is impossible to standardize and create better prints without determining and documenting best practices, and this requires a little downtime. The blending tests demonstrate the best method and standard for creating extra colors without frequency issues, underbases showing, or a lot of dot gain. The reality is that you don’t need to conduct this test more than once, as long as equipment and other printing parameters (e.g., mesh tension) don’t change. Running the test establishes an ideal scenario that you can recreate to standardize and reduce ink costs, speed up production, and help prevent a lot of press downtime.


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