Essential Topcoat Tests: 3 Key Methods For Ensuring Durability
Types Of ASTM Tests For Specifying a High-Performance Topcoat: Differences & Importance
Before specifying a high-performance topcoat, it’s essential to consider various ASTM tests. These tests combine accelerated weathering with real-life exterior exposure, providing an efficient and effective testing process.
Architecturally exposed structural steel (AESS) is used for water tanks, public art, and bridges, and the long-term color and gloss properties of protective coatings are crucial for the project’s image. The design should be built to provide a large service, a low cycle cost, and the most sustainable solution to avoid repainting or repairs caused by corrosion.
Case histories, real-world testing, and accelerated testing are the best ways to give owners the confidence that the coating system is up to the task. These three ASTM tests should be considered when making a high-performance topcoat.
1. UV (Lab/Accelerated) Testing: The Role Of ASTM D4587 In Topcoat Durability
ASTM D4587 (Standard Practice for Fluorescent UV – Condensation, Exposures of Paint, and Related Coatings), also known as QUV, is performed in a lab. It is widely used as it gives fast and reproducible results. This test mimics two main causes of topcoat degradation: UV radiation and moisture by exposing panels to UV light and condensation cycles.
For comparing the test results, you should look at the number of hours tested, then the reported color change and gloss loss. This test allows some variations that can affect the color and gloss numbers, so you should keep this in mind. The type of lightbulb used can affect the topcoat’s performance differently. UVB-313 bulbs, for example, include the shortest wavelengths found in sunlight. A significant portion of this solar radiation does not reach the Earth’s surface and is typically used to quickly screen different resins. On the other hand, UVB-340 bulbs use a wider spectrum that includes wavelengths not emitted by the sun. It’s important to review the testing information to determine which cycle was used, as variations in the UV-condensation cycle can impact the test results.
2. EMMAQUA (Natural + Accelerated): How ASTM D4141 Mimics Real-World Conditions
ASTM D4141 (Standard Practice for Conducting Black Box and Solar Concentrating Exposures of Coatings), also known by its trade name EMMAQUA, is an accelerated outdoor test. This test is conducted using a rack with 10 mirrors that track the sun. The test concentrates the solar radiation onto the coating. Then, it periodically sprays high-purity water to degrade the film. EMMAQUA results are measured in total energy exposure, reported as megajoules per square meter (MJ/m²), rather than in hours.
3. South Florida Marine Exposure: The Ultimate Real-World Test For Topcoat Resilience
South Florida marine exposure provides the most correlative real-world results, though it takes time to get to see them. This test involves placing panels in a rack along Florida’s southern coast at a 45-degree angle. Corrosion, film defects, color changes, and gloss reduction are evaluated over time. A combination of high UV levels, humidity, rain, and ocean salt spray gradually degrades the coating film.
These results are typically measured in years. Due to natural exposure, some coatings may take five, ten, or more years to produce meaningful results. Newer coating technologies may not yet have information.
B&W Distributors: Your Trusted Partner For Topcoat Testing & Corrosion Protection
Testing your topcoat is crucial for ensuring it is durable and that you are choosing the best option for your industry and avoiding periodic repairs or replacements. If you are looking for high-quality top coats that meet your needs, region, and industry requirements, reach out to us. At B&W we are here to help you decide which option is the best for you. We believe that testing matters and, as your Arizona corrosion protection team, we can advise you on the best tests for your business. Contact us today!
B&W DISTRIBUTORS INC.
Tel: (480) 924-8883
Email: info@bwdist.com
Web: https://www.bwdist.com/
ARIZONA
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Mesa, AZ 85215
