October '16

For the Business of Apparel Decorating

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58 || P R I N T W E A R O C T O B E R 2 0 1 6 What are some of the advantages of using honeycomb aluminum platens on an automatic press versus the more traditional heavy metal type? Traditional metal platens are heavy. As an au- tomatic press starts and stops, this weight puts extra stress on the motor. Another issue is that, especially during flashing, heavy metal retains heat, which can cause issues with premature gelling of water-based inks during production. Honeycomb platens are made of aluminum, so they are both light and hollow. The honey- comb pattern provides mechanical resistance, allowing it to endure millions of press rotations. In addition, aluminum is a much easier metal for controlling the temperature of the platen, and consequently is a better choice when using water-based inks. What's more, honeycomb platens arguably hold sharper details and finer dots. JEFFREY PAUL, RYONET Honeycomb platens can help prevent premature gelling of water-based inks and can last through mil- lions of press rotations. (Image courtesy Ryonet) What kind of exposure unit is best for a screen-printing operation? As with most screen-printing equipment decisions, the "best" choice in exposure units depends on your budget, capacity, and type of printed graphics. The lowest-cost option is a fluorescent exposing unit for a reason: fluorescent UV bulbs are relatively inexpensive but weak, requiring long exposure times. A larger drawback, however, is the scattered nature of fluorescent light, which ema- nates 360 degrees from the bulb, causing light to pass through the glass at angles ranging from 90 to 200 degrees. The lower the angle of light, the more it under- cuts the film positive, reducing edge sharpness of the stencil and printed image. To reduce long exposure times, fluorescent bulbs typically are positioned close to the glass, which worsens the problem of undercutting. Units with LED bulbs are more expensive initially, but offer superior effec- tiveness in several ways. First, they project bright light directionally, and can be positioned farther from the glass, achieving significantly greater "columniation," or light projected perpendicular to the glass, with the least amount of undercut- ting. They also offer uniform spacing and emit precise wavelengths of LED light. As a result, exposures are 10 to 15 times faster than with fluo- rescent bulbs, more uniform from edge to edge, and significantly sharper, especially with smaller type and process-color halftones. MARK VASILANTONE, VASTEX SCREEN PRINTING

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