Accelerated Weathering Testing: Q-TRAC Natural Solar Concentrator

The Q‑TRAC natural sunlight concentrator provides an excellent combination of the speed of accelerated testing and the realism of natural sunlight. This allows the Q‑TRAC to produce results that are both fast and accurate. Q-TRAC solar concentrator testing is ideal for a range of durable materials that can withstand high-temperature service environments

In this blog post, we explore the basic functions and benefits of the Q-TRAC, explain how specimen mounting impacts the efficiency and value of your testing, and review international standards that the Q-TRAC can help you meet.

How Does the Q-TRAC System Work?

The Q‑TRAC is unique among accelerated weathering tests because it doesn't rely on artificial light sources. It concentrates outdoor sunlight onto test specimens using a series of 10 focused mirrors, allowing it to deliver up to 5× more UV radiation than typical natural outdoor weathering testing. The mirrors are capable of reflecting about 80% of the sun's UV radiation onto the specimen target board. Q-TRAC solar concentrators track the sun during the day in both the azimuthal and vertical directions to maximize the sunlight received. Since this tracking and reflection require a clear day, Q-TRAC testing is only offered at our sunny Q-Lab Arizona Desert Testing location.

Q-TRAC testing takes place at elevated temperatures, both from the hot ambient desert conditions and from concentrated sunlight. Although cooling fans are used to reduce temperatures, tests are typically 20-30 °C higher than conventional outdoor backed exposures.

Optional water spray is available for Q-TRAC testing as well, as described in major testing standards. Some variants apply short water sprays during the day to produce thermal shock; others apply more consistent water spray during the nights to simulate the high water uptake in areas like Florida.

This approach to delivering concentrated, natural sunlight reduces testing time while delivering accurate, realistic results. 

What Types of Materials Are Best Suited to Q-TRAC Testing?

Q-TRAC is ideally suited to very durable materials, especially those with good resistance to high temperatures. Commonly-tested materials include coil coatings, powder coatings, roofing, building materials, and automotive parts. Some plastics can be tested as well, but not all plastics - be sure that your polymers can withstand high temperatures. Black panel temperatures in Q-TRAC testing can reach 100 °C, although temperature-controlled testing keeps temperatures closer to 70 °C.

What Specimen Dimensions Are Allowed?

To get the most value from Q‑TRAC solar concentrator testing, proper specimen sizing and mounting are key. Here’s a breakdown of what you need to know:

Specimen Length

The Q‑TRAC target board has a maximum specimen length of 5.5 inches (14 cm). "Length" here means across the short axis of the target board (top to bottom in the image you see above). Specimens longer than 5.5 inches have to be rotated along the target boards long axis to accommodate the extra length. Since Q-TRAC tests are billed by the total occupied "width" along the long axis of the target board (left to right in the image above), longer specimens will incur extra costs.

To ensure the best value for your testing, make sure your specimens stay within the 5.5-inch maximum length. This allows for optimal sunlight exposure while minimizing costs.

Specimen Thickness

Specimen thickness plays an important role in cooling. The Q‑TRAC system uses airflow to avoid overheating by cooling specimens as they undergo exposure, but specimens that are too thick can obstruct airflow and lead to uneven cooling. For consistent results, specimens should be no thicker than 1 inch.

In addition, a best practice is to use specimens that all have a uniform thickness. This ensures even cooling across all specimens and reduces temperature variations. Backed and unbacked specimens can both be placed in Q-TRAC solar concentrators.

How Are Q-TRAC Tests Timed?

Testing in a natural solar concentrator is typically measured by the radiant dosage received, typically in units of MJ/m². As a result, tests proceed more quickly during the summer months, when more sunlight is available.

Can Q‑PANEL Standard Substrates Be Used for Q-TRAC Testing?

Yes! Q-PANEL standard test substrates are well suited for preparing Q-TRAC specimens used for evaluating coatings performance. We have a variety of aluminum and steel Q-PANEL substrates available with a 5" long dimension, making them an excellent fit with the Q-TRAC target board.

What Test Standards Can the Q‑TRAC Perform?

The Q‑TRAC complies with all major international natural solar concentrator test standards, including:

• AAMA 305
• AAMA 623, 624, and 625
• ASTM D4364
• ASTM D5722
• ASTM G90
• ISO 877-3
• SAE J1961

A summary of some natural solar concentrator testing cycles is shown in the table below: 

Conclusion

The Q‑TRAC natural sunlight concentrator is the ultimate tool for fast, effective, and accurate accelerated outdoor weathering testing. It delivers 5× the ultraviolet irradiance of a typical outdoor exposure, while using natural sunlight for maximum realism. Test parameters can be selected to control specimen temperatures and deliver liquid water spray. Properly-sized specimens maximize your exposure area, minimize temperature differentials, and keep costs low. Q-TRAC solar concentrators can meet the requirements of all major international standards, so you can trust that your results are globally recognized.

In short, Q-TRAC solar concentrators deliver:

• Fast, Accurate Results
• Full-spectrum natural sunlight
• 5× the UV of a natural outdoor test
• High temperatures (temp limiting available)
• Water spray and nighttime freezing cycles 

Click below to learn about this highly-effective accelerated outdoor weathering technology.

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