The science behind products that sparkle and shine
Picture two cars in a showroom – one is coated in a dull, rough paint, while the other is glossy, with a hint of metallic sheen. Which one would you choose?
You’re not alone – it has been repeatedly shown that for ‘luxury’ products like cosmetics or automotive paint, appearance has a significant impact on consumer choice. Appearance is also important at the quality control level, because it can often flag issues with the reliability of production techniques to manufacturers.
But accurately defining the characteristics that give an object its unique appearance is not without its challenges. Size and shape may be easy to measure, but what about visual attributes such as colour, gloss, texture, translucency or sparkle? Believe it or not, many industries rely on characterisation and quality control carried out ‘by eye’, making it highly subjective. With manufacturers of special-effect pigments producing ever-more sophisticated compounds, there is a clear need for measurement standards in this space.
That’s where the Measurement Standards Laboratory (MSL) comes in. Through a Joint Research Project – xDReflect – that involved seven other National Measurement Institutes (NMIs) and twenty industry collaborators, they developed traceable tools and methods to optically characterise a range of novel surfaces. The xDReflect team mostly explored glossy materials and goniochromatic (often referred to as iridescent) paint, which changes colour when illuminated or observed from different directions. To characterise these surfaces, they had to measure light scattering, and for that, they used MSL’s new, primary goniospectrophotometer.
Goniospectrophotometers are instruments that can directly measure an object’s bidirectional reflectance distribution function (BRDF) – a factor that precisely defines how a surface scatters light at different wavelengths, making it a key contributor to a surface’s appearance. Within the project MSL developed a new detector in collaboration with the Czech Metrology Institute that has a very wide dynamic range. This allows it to accurately characterise dark surfaces, which are typically challenging because they scatter so little visible light.
One result of the research project is that the MSL system – built here in NZ – is now one of a small number of traceable goniospectrophotometers in the world. In addition, the project team developed a common language for the measurement of light scattering, which will be integrated into documentary standards for gloss and BRDF in a follow-on project called BiRD. Further work will establish definitions for sparkle and graininess.
These tools will provide industry with ways to objectively, and traceably, characterise materials with novel optical properties. And with collaborators that included Toyota, BASF, Maymó cosmetics and Saint-Gobain, we can expect many more products that use science to stand out from the crowd.
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The Measurement Standards Laboratory (MSL) is New Zealand's national metrology institute. Our highly skilled scientists can work with you to solve your measurement problem and improve your products and processes. We’ve helped clients in the food and beverage, consumer goods, energy, medicine, agriculture and aviation industries, supporting New Zealand’s ongoing international trade.
We understand that every R&D problem is unique, so why not contact us to discuss your specific needs? The first hour of advice is free, and new R&D customers may be eligible for a discount (up to 50%) for consultancy services.