Weathering the Test of Time

There’s a story attributed to Henry Ford and the development of the Ford Motor Co.’s blue oval logo that speaks volumes about the importance of long-lasting graphics. Ford reportedly told a designer he wanted the end result – Ford’s signature, blue oval – to not only look great on a late-model car on the road, but even after it reached its final destination – the junkyard. Ford knew graphics that were initially attractive might not remain so during a product’s lifetime. He also knew it wasn’t just a blue logo; it represented his name and the company’s brand image, and he wanted it to appeal for years.

Today, customers still want durable graphics. Like any other graphic substrate, vinyl endures gradual beatings from sunlight, heat and moisture, which trigger such problems as color and gloss fade, cracking, chipping and delamination.

However, graphics applied outdoors aren’t the only ones at risk. For example, indoor malls often feature graphics subjected to sunlight or fluorescent lighting, which can also affect appearance and performance.

Weathering performance

How do you know graphics will maintain long-term color consistency and color matching? And, what methods can determine how long graphics will look good outdoors?

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First, always use reputable suppliers, and ask about weathering data available for their products. If your graphics will be installed outdoors, ask how and where weathering was done, and if a complete graphic was tested or just a film sample.

Outdoor-weathering tests involve placing film samples on a substrate and leaving them outdoors for years to see how well they retain their color and resist sunlight, heat, moisture, mold and mildew, pollution (mostly acid rain), freeze/thaw cycles, hail, snow, blowing sand or debris. Although every material degrades with time, the resistance to such changes varies greatly.

Ideal tests occur at multiple sites under multiple climactic conditions, such as those encountered in Florida (hot and moist conditions), Arizona (hot and dry conditions) and Minnesota (hot and cold extremes). The results reveal how materials perform amidst a climate cross-section.

Nothing replaces outdoor weathering test data to determine films’, inks’ and adhesives’ useful lives. However, indoor testing can be conducted in laboratories using machines that mimic and artificially accelerate weather conditions to provide solid data about product performance more quickly.

Since the 1920s, when the Fade-O-Meter – a device designed to cause materials to fade – was introduced, companies have sought to determine how their products weather over time. During the 1940s, the development of a carbon-arc lamp facilitated weathering acceleration. At least one film manufacturer has conducted this type of product testing since then. Thereafter, evolving simulators have better replicated light and weathering exposure.

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Testing questions

Ask your film manufacturers if they conduct outdoor or accelerated weather testing on complete graphic constructions. The best accelerated tests today use full-spectrum, xenon-arc lamps. Some suppliers use sun lamps, but these provide poor weathering test data and only confirm that a film meets a minimum specification. Also, testing equipment should be calibrated and verified regularly.

Ask your suppliers how testing was conducted, who conducted it and how the data was interpreted. Keep in mind that “test houses” (independent testing organizations) will perform requested tests on materials to meet ISO or similar standards, but they don’t typically interpret the test results and aren’t experts with the materials they’re testing.

An ISO certification might not convey meaningful media-weathering information. For example, ISO 17025 specifies that the applicant meets general competency requirements to conduct tests or calibration – perhaps a minimal requirement for a reputable testing house. ISO 9001 signifies product-development certification, which means a product manufacturer has met certain standards.

Key expertise

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There are advantages to purchasing from suppliers that operate their own weathering testing facilities inhouse. These suppliers feature onsite experts who conduct research on weathering of their products, which provides them in-depth experience with material performance.

These experts frequently develop proprietary tests that predict product durability. In my opinion, these tests exceed other industry-measurement standards, which emulate benchmarks established by ISO, American Society for Testing Materials (ASTM) and similar organizations.

Based on experience, company experts understand how new products will perform, and they’re motivated to enhance durability projections. Accurate predictions of product performance enable meeting customer expectations.

Reliable warranties

Film manufacturers should offer matched components and materials with stable initial characteristics, and understand materials degradation. Film, ink and adhesive enhancements allow some manufacturers to confidently offer warranties for five or more years. Naturally, a project’s location and application will somewhat influence product warranties. Films warranted to last five years or more cost more, but peace of mind often outweighs price.

Buy from suppliers with a proven track record. If they’re confident about their products, they’ll back them with meaningful warranties. Be sure material warranties exceed your planned application, and ask what remedies your supplier provides should the materials fail before the warranty expires. And, like Henry Ford, think long term. If a material fails, it doesn’t just affect the graphic – your customer’s reputation and image also suffers.

Kenneth M. White is a senior research specialist at 3M’s Weather Resource Center.