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Selecting a Flash-Curing Unit

(November 2008) posted on Tue Nov 04, 2008

Don't get burned by selecting the wrong type of flash-curing system for your shop. Here you'll find out how flashing technologies differ and get tips for assessing the performance of flash units.

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By Rick Davis

Bringing a flash-curing unit onto your production floor gives you the ability to expand your garment-printing program to include dark garments, multicolor work, and designs that involve the use of specialty ink formulations. The primary goal of a flash unit is to properly gel a printed underbase prior to overprinting. Heat is heat, which makes the selection of a flash unit capable of performing this task fairly simple for many. Almost any heater is capable of producing temperatures sufficient to gel an underbase. However, one aspect that’s often overlooked is the residual effect that the flash unit can have on other parameters of the printing process. This month, we’ll look at different types of flash units and discuss their influence on the production of screen-printed garments.


Black body

Black-body flash units are the most widely used in the industry. These systems either work off of a thermostat, which controls the panel temperature by maintaining a constant temperature within x degrees, or a percentage timer, which maintains a ball-park temperature by turning the unit on for 50% of the time (say 5 seconds on and 5 seconds off). Of the two, the thermostat models are far more accurate at setting and maintaining a constant temperature.

The need for consistency in the flashing process is obvious. Any wide variations in flashing temperature can result in problems ranging from erratic after-flash tack to intercoat-adhesion issues between the underbase and overprinted colors. A good flash unit will maintain temperatures within ± 25°F.

Black-body flash units that employ hot air offer some versatility over standard black-body systems. As with large, gas-fired dryers, the addition of hot air to the flashing process can de-crease flash times because the ink film will absorb the heat more readily. Although the air can offer advantages, caution must be exercised to ensure that the ink film receives a uniform dispersion of heat and that the areas directly under the air knives do not receive an excessive amount of heat, which can result in a spotty underbase and potential intercoat-adhesion issues.

Most black-body and black-body units with air movement operate on either 110 or 220 v. Always know your building’s power limitations before you call the manufacturer or your supplier so that you can explain to them what you need and can handle.


Quartz flash units


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