Davis presents eight ways to build a better textile-printing operation, including a standardized procedure that ensures consistent quality from production run to production run.
By Rick Davis
With the drive for increased production efficiency and the popularity of specialty applications, such as high-density printing, the need for consistent and uniform stencil thickness has become more critical than ever. As printers attempt to print smaller and smaller degrees of detail and extreme levels of acutance, it's more important than ever to produce uniform and consistent stencils from screen to screen and job to job, regardless of the mesh count. For this reason, many larger shops have invested in automatic coating machines, which offer more control than manual emulsion coating.
3. Screen tension
Of all the procedures in the facility that impact quality, none is as crucial as the ability to deliver consistent and adequate screen tensions. Virtually every aspect of print quality is determined by the tension of the screen, including the following characteristics: hand (softness) of the print, total ink-film thickness, opacity, resolution, saturation of process-color prints, and registration accuracy.
Besides influencing what you see in the print, screen tension also affects how you set other processing parameters, such as squeegee speed, pressure, and angle, as well as off-contact distance. These settings influence both print quality and production speed.
The key is to establish the minimum requirements that meet your quality standards. Document your tensioning (and retensioning) procedures, then make sure these standards are always applied. Every screen that goes to press should be in "new screen condition" if your procedures have been followed correctly.
4. Flashing temperature
As I have mentioned on many occasions, printers have a "more is better" mentality. This is why many do not study and standardize their flashing procedures, but simply run their flash units as hot as possible in the name of productivity.
When printing with higher screen tensions and thinner ink-film thicknesses, the need for higher flashing temperatures diminishes. The problems that are caused by excessive temperatures include scorched fabric, ink blistering, dye sublimation on synthetics, poor intercoat adhesion between different ink colors, and remelting of ink films.
I have seen flash units with digital controls set as low as 450°F (230°C)--1/3 of the unit's output limit--that still gel printed ink properly. By standardizing flashing procedures to run cooler rather than hotter, you can minimize the occurrence of troublesome variables associated with higher temperatures.
5. White-ink usage
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