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Curing Common Mistakes in Pad Printing

(October 2009) posted on Mon Sep 21, 2009

Troubleshooting the pad-printing process requires the identification and control of associated variables. The tips presented here will help you avoid some of the persistent problems you encounter on press.

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By Julian Joffe

If I had changed the ink formula to something with more thinner or added some retarder the day before, I would have realized that the ink was too dry and that the deeper cliche I made helped to mask the problem. The true problem was simply that the ink was drying out on the cliche. When I deepened the etch on my cliche, I compensated for a drying problem. Changing the pad made no difference. I spent three hours messing around with possible solutions, and we ended up running the print job at a loss.

Thinking about what is happening and the cause-and-effect of what you intend to do, or have done, is the right approach. Additionally, there are usually several solutions to a problem. The question is really: How do I find the simplest, least costly solution? In this case, making a new cliche costs a lot more than simply adding some retarder to the ink.

The variables
The following list identifies some of the most common variables in pad printing. Controlling these variables prevents common mistakes from hindering your productivity.

• Pad size and shape (curvature), durometer, and material choice
• Ink composition and viscosity
• Composition and evaporation speed of thinners
• Substrate type (plastic, metal, glass), texture (roughness), and shape (curved, flat, compound)
• Cliche type (steel, polymer, aluminum), etch depth, and etching technique
• The artwork/positive, including orientation, screening, detail, image type (surface coverage), and method of printing
• Machine settings, including speeds, pauses, strokes, and positioning (pad tooling, orientation)

Pad selection
Pad printers often overlook the importance of pad selection and its overall effect on the success of the printing process. Too often I consult with an operator who is encountering problems with ink transfer. Common difficulties include partial image transfers, pinholes throughout or in portions of the print, and/or distortion of the text or logo. Often these problems are caused by incorrect pad selection for the particular print project.


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