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And you think you have problems...

(September 2003) posted on Fri Oct 17, 2003

Visit a printing facility where standard operating procedures, equipment maintenance and cleaning, and production procedures are failing.

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By Carol Swift, Peter Kiddell

The company had been operating for 20 years, printing not only decorative graphics, but also critical safety information. Our assessment of the facility identified 61 points in their printing processes where action needed to be taken to ensure safe, accurate, efficient production of a quality product. As these points had not yet been addressed, it was clear that their product quality was inferior. To what degree? Well, put simply, the inks they printed just didn't stick to their substrates.

Now, you would have thought that 20 years of printing experience would have taught the company's employees how to select ink that adheres to their product. Apparently, they had successfully chosen and printed the appropriate inks in the past. But as it turned out, they had trouble years before their print guru left. Maybe their guru was like so many in that he was an expert at resolving problems he had created himself. Over the years he and the rest of the team became conditioned by bad practice, which resulted in the situation described here.

The screen inks the company used were well matched to the materials for which they were intended and included single-component and two-component UV-curing inks. But by their natures, the substrates were difficult to get ink to adhere to, which made the applications arduous. These challenges made it imperative to mix the inks according to the manufacturers' technical-data sheets. Unfortunately, the inkroom personnel did not know where the data sheets were, and each mixed the inks to his or her own liking. There were electronic scales available, but they were inaccurate and rarely used.

The ink technicians were convinced they could determine correct mixtures based on how the ink flowed from their wooden spatulas. Sometimes the inks just needed a couple of squirts of solvent to perfect the mix. An onlooking ink technologist would have broken down in tears at the sight of the mixing practices.

With two-component inks, the amount of catalyst used has to be mixed in a precise ratio to the base ink. This is particularly the case when adhesion is difficult. Inks also must be cured as specified by the ink manufacturers. Otherwise, the full characteristics of the cured ink will not develop. This results in poor mechanical and chemical resistance, in addition to inadequate adhesion.


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