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Catching the On-Press Culprit

(February/March 2019) posted on Mon Mar 04, 2019

Whether it was the art, screen, ink, or a combination that caused your job to go south on press, here are four steps you can take to identify the snag – and prevent it from happening again.

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By Thomas Trimingham

The downside to printing tiny shapes like dots is that ink has a tendency to stay stuck in them. When this happens, the press operator will notice that the design looks faded and the natural instinct is to increase the squeegee pressure to force the ink out of the screen and onto the garment. But the result is that dots will get flattened out. Over time, they will start to bleed into each other and then slowly begin to fill in until they get darker and darker. After several dozen prints, detail will be lost and the image will look quite different. Then, the press operator will often wipe off the bottom of the screens and the print will go back to its original lighter tone before darkening again after several more prints. The net result of this seesaw dot gain is that the shirts in the order will look different depending on where in the job they were printed. (See Figure 2.

Here’s a simple fix if dot gain is a common challenge in your shop: Create a separate set of inks for detail work that are all lower in viscosity. This bypasses the problem of the ink being too thick to easily flow through small details in the stencil, so your operators won’t feel like they need to use more pressure or have to contend with ink buildup on the back of the screens. Contact your ink manufacturer and do some testing to find the ideal viscosity level for your detailed prints. 


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