Q-Lab is excited to announce the official release of the brand new TUV-421 lamps for QUV accelerated weathering testers. These innovative lamps help distribute a much broader spectrum of light, in comparison to your typical UVA-340 fluorescent lamps, while continuing to provide the same excellent spectral match for shortwave UV light. 

The graph below shows Spectral Irradiance curves for an outdoor daylight, a xenon arc lamp with a Type I Daylight filter, a UVA-340 lamp, and a TUV-421 lamp. Each is shown scaled to a realistic value, either in the laboratory or outdoors. You can see that the TUV-421 lamps provide an very good spectral match for daylight in the shortwave UV. In fact, TUV-421 lamps meet the definition of a Type I Daylight filter as defined in ISO 4892-2 and ASTM G155. Additionally, the TUV-421 lamps continue to replicate the sun's output, up through about 430 nm.

The primary benefit of TUV-421 lamps is to test for color fading in materials with colorants that are susceptible to longer-wavelength UV and shorter-wavelength visible light. This can include pigments and dyes found in textiles, printing inks, paints, plastics, and more. Color changes observed in service environments may not be reproduced when testing with traditional UVA lamps, but the extended spectrum of TUV-421 lamps corrects that. Preliminary testing conducted by Q-Lab demonstrates that TUV 421 lamps do indeed induce color change in some cases that UVA 340 lamps do not. This offers, for some materials, a superior correlation with full-spectrum xenon lamps and outdoor testing. An example of this is shown below for black ink printed at different levels of darkness from 100% to 10%, as one looks left to right. The UVA-340 exposure looks very much like unexposed inks, while the TUV-421 and xenon arc both show very similar degree and character of color fade.