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Special Effects on Automatic Presses

(August 2009) posted on Fri Aug 07, 2009

Tips for Cutting-Edge Garment Graphics in High Volume

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You’ll always have a clearly defined print area that you cannot alter, regardless of whether you use oversized, conventional, or smaller screens. This is but one of the defined parameters within which the designer must work. Another is the speed at which the machine can run in production, given the type of special-effects design.

The rules that apply to manual screen printing also apply to garment decoration on an automatic press. You still need to set, monitor, and—if necessary—adjust off-contact, squeegee pressure, screen tension, and flood and stroke speed. The big issue is the need to adjust while the machine is in the middle of the production run. Try your best to avoid adjusting the press while a job is on it and keep in mind that adjustments are stoppages. The need to make a serious adjustment may require you to start the job from scratch. A thorough sampling process greatly reduces or eliminate on-press adjustments because the process give you the chance to dial in press settings ahead of the game. Once again, sampling and investing time in R&D are important contributors to efficient production of special-effects-driven garment screen prints.

Maintenance is obviously an important issue with automatic screen-printing machines, just as it is with any equipment you own. Never underestimate the seriousness of keeping all of the press’s channels lubricated and platens leveled. You should level a press’s platens no less than once a month, if not weekly. The impossibility of trying to achieve a smooth and even gel print using a 300-micron screen on platens that are not level would quickly become apparent to anyone who tries. Gels don’t contain the blowing agents or thickeners common to high-density inks. Like most inks, they lose viscosity during long printing runs due to the buildup of heat and friction. To apply a 300-micron-thick ink film evenly requires that both sides of the image area have the same off-contact setting. This is especially critical when the gel has lost some viscosity.

Uneven platens will make one side of a print look inferior to the other. The image may appear mottled, or it might simply collapse. This rule also applies to high-density inks and other formulations that require the use of thick stencils. Bottom line: Failure to keep your platens level negatively affects off-contact, so it follows that print quality also will suffer.


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