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DAMPENING SYSTEMS -- Striking a Balance

September 2003
BY MARK SMITH


Heavy iron, a moniker for presses that conveys size and brute force, has been supplanted by talk of electronic controls, digital integration and computerization. Lest anyone forget, the real magic of lithography still happens when ink and water (fountain solution, to be precise) meet on the plate.

Mechanical systems are what make a press, even if an increasingly more electronic face is being put on them. None play a more central role in the offset printing process than the dampening system. The fundamentals are the same for web and sheetfed press applications, but the solutions of choice tend to differ.

Delta dampening is the de facto quality standard for half- and full-size sheetfed presses, asserts Michael Barisonek, vice president of sales and marketing at Epic Products International in Arlington, TX. To date, the web market hasn't had the same quality demands, even for heatset work, as the sheetfed segment, Barisonek adds. "That is changing, though."

Spray dampening is considered by proponents to be the current standard-bearer for web applications. Advancements in spray dampening controls, valves and precision nozzles have made spray systems suitable for printing on coated stock with a higher level of quality than ever before, asserts Dennis Schupp, vice president of operations at Smith RPM Corp. in Lenexa, KS. The manufacturer's spray dampening systems are sold by Pressroom Products in the United States.

"Water spotting, pulse marking and striping—which all previously were quality issues with spray dampeners—have been eliminated in today's high-speed, digital pulsed systems," Schupp says.

Baldwin Technology, based in Shelton, CT, put together a position paper to make its case for spray dampening on web presses. A key benefit of the technology, it argues, is a reduction of performance variances.

Getting Stable

"Spray dampening technology is designed to reduce and, if possible, eliminate sources of change, thereby stabilizing the process and improving both quality and productivity," the piece notes. For the most part, this is accomplished by simply eliminating mechanical parts. Delivery of fountain solution using a spray mechanism can do away with brush and pan roller systems (rollers, motors and gearbox), belts, pulleys and bearings, for example, the company points out.

According to the manufacturer, pressroom temperature is another variance factor and can impact the amount of water delivered by open dampening systems, which rely on surface tension for transfer. Similarly, contamination is of particular concern with brush dampening systems, the position paper continues. Ink-matted bristles will not transfer water properly, so the operators start cleaning the brushes with blanket wash, which winds up in the fountain solution and can lead to scum, toning and tint problems.
 

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