The light stability of transparent coating materials is influenced by the location of exposition

Abstract

The ultraviolet radiation (UV), reaching the earth‘s surface, changes color of the paint films. By exposure to weathering, the biggest damage is caused by light, especially short-wavelength UV, high temperature and humidity. Any of these factors can lead to degradation. These natural elements can be reproduced and accelerated in laboratory conditions in test devices, such as the fluorescent UV or xenon-arc test chambers. Such equipment can provide fast and reproducible results. The artificial aging is a useful tool for product research and it is required by many international standards. A major problem in comparing the outdoor and laboratory tests is the fact, that the weathering-chamber enviroment is well controlled, whilst nature is not. The outdoor exposure tests are influenced by many factors, such as altitude, local conditions, seasonal variations, orientation of the sample and variable properties of test materials. Our work compares the influence of altitude of the tested position on light stability of surface finish treatment. The color changes are observed on different kinds of coating paint films with different contents of chemically binded UV stabilizator. Furthermore, the influence of bolstering material was observed. This material was mostly made of woods from temperate clima zone. One tropical wood was used for this purpose as well. The color changes of paint films (∆E) on different bolstering materials were assessed by spectrophotometer.

Keywords

• light stability
• wood
• finishing materials
• spectrophotometer
• UV stabilizer