According to Vermillion at Eye Applied Optix, this validation is all part of the continuous process of improvement in testing. “For both compliance testing and for R&D, you need to review results to make sure they make sense.”

Above: Car maker Ford was part of the consortium that developed the ASTM D7869 test method, which recog- nises the important role of moisture in polymer weathering

Xenon Arc Exposure Test with Enhanced Light and Water Exposure for Transportation Coatings), was published in 2013 after 10 years of development by a consortium that included car maker Ford, weathering equipment and other suppliers. Although initially developed as a weathering method for coatings, it has recently been adopted in certain plastics markets. The researchers realised that moisture uptake was a more significant issue than previously thought, says McGreer. They determined that weathering was affected by a synergy of specific wavelengths of light, temperature’s effect on the rate of reaction, and moisture causing physical degradation. The new test uses cycle parameters designed to match south Florida conditions, and researchers in the consortium believe it gives a more accurate representation than previous methods.

As with any new weathering test method, there is a challenge in how to correlate data from the old method with the new. This will take place as people use the new method, says McGreer, and use will become more widespread once the new method is written into standards (for example, automotive supplier standards). “Validation with real world data can take three to five years,” says McGreer. “You need to make sure that you are not getting false failures. You need to identify good parts as good and catch the bad parts.”

Xenon innovation Last year, Atlas Material Testing Technology introduced its next-generation instrument in xenon- arc weathering testing, the Ci4400 Weather-Ome- ter, which replaces the previous Ci4000 model. The new model provides test results that are consistent with legacy instruments, but it has improvements such as more efficient air flow for better tier-to-tier and within-tier uniformity, better PID control of parameters for greater reproducibility, and a new deionised water-cooling system for greater reliability. Other new features include a larger chamber door, a 10% increase in specimen capacity with no increase in footprint over the previous model, an improved rotating specimen rack, and an optional AIOS (All-in-One Sensor) sensor to measure irradiance, chamber tempera- ture, and relative humidity at the specimen expo- sure plane. The last in that list is a significant addition in

terms of stability. “The system may be controlling at set points as required by a standard, but what is actually happening at the sample plane, especially in terms of the air temperature and humidity, may be quite different in different sizes or different configurations of instruments. Differences in temperature and humidity could lead to different rates of degradation,” explains McGreer. The at-sample-plane sensor solves this problem because it can be used to measure at the sample plane and control to the set-points. Because the AIOS has an internal battery and storage, it can be moved to different locations. “It could be used to determine reproducibility of testing conditions (at the sample plane) in different instruments or confirm parameters at the sample plane in different makes/models of instruments to ensure ‘equiva- lency’,” says McGreer.

Q-Lab adds calibration in Germany/China

Q-Lab has expanded its capabilities worldwide for ISO/IEC 17025 calibra- tion of irradiance, temperature and relative humidity (RH) for its weather- ing and corrosion chambers. Q-Lab Germany is now officially accredited for laboratory and field


calibrations and Q-Lab China has expanded its scope to include field calibration. With these additions and reaccreditation of its existing capabili- ties, Q-Lab is fully accredited for labora- tory and field calibration from its offices in the US, Germany, UK, and China.


The accreditation procedure was carried out by the Maryland, US-head- quartered American Association for Laboratory Accreditation (A2LA), an independent accrediting body for ISO/IEC 17025. �


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