A veteran at a paper-products plant in southern Taiwan grumbled to me: after switching to water-based ink, they'd cleared the environmental hurdle, but the drying speed was noticeably slower than with solvent-based ink, and stacks at the back end kept sticking together. He asked whether he could add a bank of infrared to 'give it an extra push.' It's a very typical need — the bottleneck in ink drying is often not getting it printed, but whether it's dry once it comes off the press.
What Is Ink Drying Actually Removing?
Drying water-based ink is mainly about driving off water; solvent-based ink is about evaporating organic solvents; and UV ink relies on ultraviolet cross-linking, which falls outside the infrared scope of this article. For water-based ink, water absorbs strongly near 3µm — right in the energy-concentration region of medium-wave infrared — so medium-wave (carbon medium-wave) is a very good match for 'driving off water.' Short-wave infrared heats up extremely fast, reacting on the order of seconds, and can pour energy into the surface layer within a very short exposure time, making it suitable where line speed is high and dwell time is short; but with a thin ink layer you have to watch out for energy over-penetrating into the paper body itself.
Infrared Is Only Complete with Airflow
Here's something many people overlook: once moisture is heated and evaporates, it needs somewhere to go. If you only heat and don't carry the moisture away, saturated vapor lingers near the material surface and actually slows drying down. So an infrared drying section is often paired with an air knife or hot air: the infrared precisely delivers energy into the ink layer and accelerates moisture vaporization, while the airflow carries the vapor away. It's a division of labor, not an either/or.
On the selection side, bear in mind that paper itself has limited heat tolerance — overheat it and it yellows, turns brittle, or even scorches at the edges — so power density and conveyor speed have to move in step, and we recommend pairing them with non-contact temperature monitoring. As for whether to use short-wave or medium-wave specifically, how many kW, and how many rows of lamps, that has to be measured against your own ink formulation, paper stock and line speed; you can't just copy someone else's parameters.
Manufacturers in the Kaohsiung, Tainan and Pingtung area looking to evaluate infrared heating or improve a drying and curing line are welcome to talk through your on-site situation with TingHao Technology. If you're dealing with sticking at the back end of the press and want to look at adding an infrared drying section, add us on LINE or call 07-363-0802 — we'll look at your material conditions first, then advise.