If you're looking to add a new dryer to your garment-printing shop, this article can help you narrow your selection.
Because both the garment and ink film must absorb heat in the IR dryer, it follows that a heavy sweatshirt printed with a thick ink film requires more time in the dryer than a lightweight T-shirt printed with a thin ink film. Very thick ink films and heavy garments, such as those found in some athletic-apparel applications, can act as a heat sink. In turn, a much longer dwell time is needed to achieve a full cure. Certain specialty inks can also increase dwell time in an IR dryer, as can bright whites and inks that are made with a high pigment load. Examples include gold inks, glitters, and metallics. These inks slowly absorb IR energy delivered in the form of IR radiation and can sometimes reflect the IR energy.
In addition to managing the time printed garments must remain in the oven, you also must keep an eye on moisture in your garments and the humidity in the shop. Moisture can be the biggest obstacle to a thorough cure with an IR dryer. Only when moisture is removed from the garment can the garment and ink film begin to absorb the heat necessary to cure. Some manufacturers offer integrated air-circulation systems with their IR dryers to evacuate moisture more rapidly, increase the heat-absorption rates in garments and ink films, and keep the oven chamber temperature more consistent.
Gas dryers (Figure 2) burn fuel gas to heat air, which is then moved at high velocity to cure printed garments. The hot air penetrates the print and garment, quickly driving away excess moisture and bringing the garment and ink temperatures into curing range.
Gas dryers are typically used in shops that produce high-volume jobs. They are also recommended for shops that work with water-based garment inks. These inks dry by evaporation and require both the heat and high-velocity air movement provided by a gas dryer to cure efficiently and effectively.
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