On the floor, pick the wrong UV conveyor lamp and you don’t just slow the line. You get tacky surfaces, pinholes, and ink that never fully cross-links. Out in garment decoration, the shortwave UV versus LED UV question isn’t academic. It’s about spectral output, peak irradiance, and the photoinitiator chemistry you’re actually running. What matters, technically Industrial UV curing conveyor lamps are all about spectral control. A high-pressure mercury vapor lamp gives you broad output with strong peaks at 365 nm and plenty of shortwave energy. That shortwave punch penetrates thick ink layers and drives cross-linking deep into the substrate. LED systems, on the other hand, emit narrow-band wavelengths—commonly 365 nm, 385 nm, 395 nm, 405 nm—with fast rise/fall, so you can dose energy precisely. In practice, the specs that count are peak irradiance at the substrate plane (mW/cm²), delivered energy density (mJ/cm²), arc stability, and the lamp-life degradation curve. Reflector geometry and dichroic coatings shape the spectral distribution and keep heat off the web. Why it works where it does In garment printing, shortwave UV shines when ink films are thick, pigments are dense, and adhesion to textiles has to be solid—typical for screen and some flexo builds. LED is the move when films are thin, detail is fine, and you need a fast, repeatable cure, especially on heat-sensitive substrates where temperature rise is limited. For offset, a stable, high-irradiance lamp with tight hot-spot control keeps dot integrity and prevents set-off. For flexo, uniformity across the web keeps mottle away and color density consistent. For screen, high peak irradiance at 365 nm clears the mesh and cures the build without under-cure at the edges. The things you learn the hard way Matching lamps to presses isn’t plug-and-play. Existing reflectors, shutters, and power supplies were designed around arc lamp thermal loads and spectral profiles. LED retrofits need compatible drivers, solid thermal management, and sometimes optics redesigned to match the irradiance profile you had. Arc lamps deliver high peak irradiance and deep penetration, but they need warm-up, can generate ozone unless you use ozone-free quartz, and demand more cooling air. LEDs turn on and off instantly and draw less energy, but you have to manage heat carefully to avoid wavelength drift and premature lumen loss. Verify spectral output with a radiometer, confirm your substrate temperature limits, and make sure the lamp choice lines up with the ink’s photoinitiator absorption window.