Colour and gloss retention matters
RVs, buses, and other vehicles must face all elements. To most people who love the sun and its warmth, it might come as a surprise that the sun is actually one of the major potential threats to the appearance of their vehicle. When imagining the impact of the sun over time, consider an everyday example, like a bright-coloured curtain. After being exposed to the sun for a while, its colours and shine will fade, and its appearance will remain only half of what it used to be. Depending on the material used, the same can happen to a vehicle. While a curtain can be replaced, a vehicle is a significant investment. You want your customers to be able to step into the same shining, appealing vehicle for decades. This is not just because of the great feeling you get from looking at a beautiful vehicle, it also matters financially. Your customers want their vehicle to retain its resale value should they ever choose to replace it, and who wants to buy a vehicle that has lost its appearance? To prevent this, you can opt for a solution that provides so-called colour and gloss retention for your vehicle.
Serious measures for colour retention
So, colour retention. The example of the curtain may make this sound arbitrary: it is either faded, a bit faded, or not. However, there’s an actual measure to assess the degree of colour retention: the ∆E measure (i.e., the Delta E measure). As coating specialists, at Euramax for Mobility we are obsessed with colour and the properties of our coatings, and we strictly adhere to this industry standard for determining and testing colour retention.
∆E (CMC) measure in short
The ∆E measures the extent to which a colour differs from its origin. Therefore, we calculate the difference between two colours based on their exact positions in the colour range. One ΔE is the minimal difference visible to the naked eye. The ∆E value ranges from 0 to 100:
- ≤ 1.0: not perceptible by the human eye
- 1-2: perceptible through close observation
- 2-10: perceptible at a glance
- 11-49: colours are more similar than opposite
- 100: colours are exact opposites
At Euramax for Mobility, we make an additional correction, the so-called ∆E CMC (Colour Measurement Committee) correction. This industry-standard correction reflects the fact that the human eye is more sensitive to certain movements in the
colour range than others.
Below is a visual example of the colour retention at a ∆E CMC of about 10, after 2000 test hours. The colours are an approximation, colours on a screen will always differ from colours on a live vehicle.
Comparative analysis
We extensively assessed the colour retention of our painted aluminium. The ∆E value after exposure to UVA light over time is displayed in figure 1 (below), compared to that of plastic (GRP). As can be seen, the ∆E of our painted aluminium is far below 1 (i.e., invisible to the naked eye), even after two thousand hours of test exposure, equivalent to a test of two years of outdoor exposure in Southern Europe. In contrast, plastic has a ∆E value of around 8 after the same period, and this value increases over time. Recently developed plastic products are specifically designed for UV resistance and colour retention. To make a fair comparison, we have also tested these materials (as shown in figure 1). While these materials do indeed outperform their traditional alternatives, the ∆E value has still risen to ~5 after just two thousand hours of test exposure. Clearly, plastic cannot meet the EN-1396 norm that applies to the coating industry, even when using varieties developed for UV resistance. This norm stipulates a maximum ∆E value of 3 after two thousand hours of UVA test exposure, a standard easily adhered to by Euramax coated aluminium.
Assessing the loss of gloss
Unlike colour, gloss retention is measured simply by calculating the percentage of gloss lost. To demonstrate and compare the superior gloss retention of our products over time to that of GRP, we have measured and analysed gloss retention in relation to UV exposure over time (see figure 2 below). As illustrated, the difference in gloss retention is striking. Aluminium coated with Euramax (metallic) coatings maintains its gloss despite intense sun exposure. In contrast, plastic alternatives (GRP) lose a third of their gloss after two thousand test hours (equivalent to two years of outside testing).
Best-in-class testing method
To critically assess the impact of sunlight over a very long period of time without having to wait for years, at Euramax for Mobility we use accelerated testing with UV lights. More specifically, we use QUV-A 340 testing. Fluorescent ultraviolet UVA-340 lamps, recommended for QUV testing by the global ASTM G154 Standard. This is the best-in-class method that most closely mimics real sunlight, in the critical short wavelength region from 365 nm down to the solar cutoff of 295 nm.
We expose our paint to these lamps for up to ten thousand hours. In this article, we show results up to 2,000 test hours, which equals two years of outdoor testing in Southern Europe, where many RVs reside during holidays.
Euramax only shows true colours
We are on your side, helping your vehicle make a lasting impression by providing coatings that maintain their colour and gloss throughout the years. Thanks to our broad range of available coatings and continuous development of new coatings with beneficial properties, there’s always a suitable option for your vehicle.
Our coating specialists can assist you in finding the right solution for your vehicle and discuss trade-offs between different coatings. Get in touch, and we’ll show you our true colours.