The need for Accelerated Weathering Tester : Photo Stability of Products
- April 18, 2019
- Posted by: MahaChem
- Category: IS, Lab & Analytical Instruments
Are the colours of your product stable under the exposure of sunlight?
Have you noticed the cases whereby the colours of the clothes or drinks start to fade away after the long exposure to the sunlight? These may seem strange, but these phenomena are all due to the chemical mechanism called photodegradation. The phenomena happen as the ultraviolet rays inside the sun break down the chemical bonds of chromophores, light absorbing substances, present in the dyes of the products, leading to the bleaching. If you are facing this issue in your products, you are not alone in this.
Case Study: Interbev Philippines
Interbev Philippines manufactures non‐carbonated energy sports drinks that are sold throughout the Philippines under the Cobra tradename. There have been some products that displayed short shelf life that were unacceptable. They are considering exporting to other countries, but have concern about the photo‐stability of their product and how it compares with others. Gatorade is the recognized leader in non‐carbonated energy sport drinks in the USA and abroad. Interbev is interested in how the color‐fastness of their product compares with the industry leader using an accelerated test that could be repeated and very consistent. How were they able to do so?
It was believed that a Q‐SUN xenon chamber would be more appropriate for this colorfast test and a preliminary 24 hours test verified this hypothesis. Three Interbev flavors were selected, Berry Red, Lemon‐Lime, and Orange and three comparable Gatorade flavors were selected for comparison. After a 24 hour exposure in a QUV there was no visible change in color, however after 24 hours in a Q‐SUN, fading was obvious after the same 24 hour period. This indicates the color fade is from visual or infrared solar energy not present in the QUV.
Consequently, the Q‐SUN Xe‐3 was selected for the full comparison test. The test standard selected by the researchers is a modified AATCC TM 169. This is a commonly used colorfast test protocol and they liked using Window B/SL optical filters to simulate light through window glass, but they felt that the irradiance of 0.35W/m2 was insufficient to produce results fast enough. They opted for 0.68W/m2@340nm as the irradiance set‐point to produce faster results. The irradiance is continuous. Samples will be repositioned every four hours during office hours.
Four 40ml test samples were prepared for each of three flavors from the respective manufacturer. After each 24 hour exposure, one sample was removed from the Q‐SUN for a total exposure of 72 hours. One sample of each flavor was retained as an un‐exposed reference. At the end of the test, the samples were visually evaluated for photo‐stability and digital color measurements taken for each sample.
After the initial 24 hour exposure period, one sample of each product was removed for visual comparison with the retained reference sample. The remaining samples were subjected to another 24 hour exposure. After 24 hours of continuous light exposure, all samples displayed various degree of fading from their original color.
At 48 hours, differences can be seen in the durability of various Cobra and Gatorade products. The degradation of each product is uniquely different with different rates of degradation unique to the product.
The test was concluded after 72 hours and colors digitally evaluated with HunterLab Mini Scan XE Plus.
Of the three Cobra Energy drink samples that were evaluated, (Orange, Red Berry, and Lemon‐Lime) the one with the best photo‐stability was Orange. Even though the colors we of a different hue, the Cobra Energy Sport drink compared quite favorably with a similar Gatorade product.
Both Cobra and Gatorade displayed very little fading after the 72 hour test period. Digital color measurements validated the visual observations. Since orange is a combination of red and yellow, those digital values (A+ B) were measured and plotted for trend analysis and comparison purposes.
|ORANGE ‐ COMBINATION of RED and YELLOW||A+B values|
|RED BERRY ‐ PRIMARY COLOR IS RED||A values|
|LEMON LIME ‐ PRIMARY COLOR IS YELLOW||B values|
Are you interested to be able to conduct testing as demonstrated from the case shown above? Our weathering tester, Q-SUN, can support you to do so. For the further details, please check the following page.