Printwear

February '13

For the Business of Apparel Decorating

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Color control Table 1 we need to keep to standard on-press procedures to show that, though tweaking appeared to work that once, it isn't going to bail out a bad file or save a fouled film. For example, we are well aware of the destructive practice of reducing the exposure time to "hold the dots." One can cut the exposure time, develop and inspect the screen and erroneously conclude that "we got every dot." What actually happens is the smallest of the highlight dots are saved at the expense of enlarged shadow dots and Chromatic Thermal Hydraulic Lch color Yield point Absolute viscosity Density Gel point Yield stress Gloss Fusion point Plastic viscosity Opacity Re-melt point Surface tension There are three noticeable, quantifiable aspects of ink every process printer should know to determine the consistency of the ink before going to press. They are its chromatic, thermal and hydraulic characteristics. Each has its own subset of properties, as listed. shifted midtones. Now there is no way to hold the conspicuous colors such as those used in foods, skin-tones, neutral grays, logo colors, and so on. Another screen room sin is to push the mesh count too high and forget it is the stencil that holds the detail (conversely, the only detail the mesh holds is the stencil). Exceedingly high mesh counts not only delay setup and timeto-color, but they severely curtail runtime as well. And remember, press time costs more than $3 per minute. Any chance the ink is calibrated? Once the rest of the system, including the press, is standardized, we'll need to know if the ink in use is consistent. This is the missing piece to the puzzle to make the results predictable. The three questions to answer in respect to inks are: what color it is; how it responds to heat and how it flows. There are three noticeable, quantifiable aspects of ink every process printer should know to determine the consistency of the ink before going to press (see Table 1). First, the chromatic (color) aspects are all measured at a specified deposit in mils. These include: Lch (luminosity, chroma and hue) of the color, the intensity (or reflectiondensity) of the ink; its 60ยบ gloss level; and finally, its opacity. Every press operator with a consistent system can predict the outcome before it happens. But if the ink is way out of spec, you'll never figure out how to make it work. 60 | Printwear PW_FEB13.indd 60 continued on page 93 February 2013 1/18/13 10:09 AM

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