Q-Lab Launches New Breakthrough in UV Fluorescent Testing with TUV-421 Lamps

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.

Unlike most fluorescent lamps, there is a minor change in spectrum over the life of the lamp. As the lamps age, the output beyond around 380 nm starts to drop. After 2,000 hours of testing at typical irradiance, the spectral output between 400 and 450 nm drops about 10%. Q-Lab’s recommendation is to change lamps before 2,000 light hours of exposure - different than for traditional UVA-340 lamps. For this reason, TUV-421 lamps are warrantied for 2,000 light hours at an irradiance of 60 W/m^² @ TUV, even though they are likely to reach setpoint longer. As shown in the graph above, this recommended setpoint is consistent with a xenon arc irradiance of approximately 0.55 W/m^²/nm @340 nm.

New TUV-421 lamps provide an extended spectral irradiance relative to typical UV fluorescent lamps. This allows you to enjoy the convenience & low cost of QUV fluorescent UV testing, but with the ability to reproduce color change effects more like one typically expects from Q-SUN xenon arc testing. These new lamps offer a simple way to test for these color changes at a very affordable price.

For more information on TUV-421 lamps, as well as any of our QUV lamp offerings, visit the QUV page here on our website or contact us with any questions.

Contact Us