GLOSS -

Gloss has been defined as the attribute of a surface that causes it to have a shiny or lustrous, metallic appearance. Gloss is a visual impression that is caused when a surface is evaluated. The more direct light is reflected, the more obvious will be the impression of gloss. As the human eye perceives gloss, it is a subjective sensation. However, control by visual analysis is insufficient because evaluation conditions are not clearly defined and people see and judge differently. Yet gloss is often used as a criterion to evaluate the quality of a product - including automotive coatings, furniture coatings, plastics, metals, and paper.

Gloss is measured using a Glossmeter, which directs a light at a specific angle to the test surface and simultaneously measures the amount of reflection. The type of surface to be measured determines the gloss meter angle to be used and thus the gloss meter model. The intensity is dependent on the material and the angle of illumination. In case of non-metals (coatings, plastics), the amount of reflected light increases with the increase of the illumination angle. The remaining illuminated light penetrates the material and is absorbed or diffusely scattered dependent on the color.

Gloss is measured by focusing on the reflected image and not by focusing on the surface. Eyesight and mood have a decisive role in the visual judgment. In order to guarantee a reliable and practical quality assurance, it is necessary to define appearance with objective, measurable criteria. Accurate characterization of appearance does not only help to control quality, but improves quality and optimizes manufacturing processes.

Gloss can be a measure of the quality of a surface, for instance poorly cured paints or coatings can exhibit unusual gloss levels and can lead to chipping and flaking at a later stage in manufacture. The gloss of a surface can be greatly influenced by a number of factors, for example the smoothness achieved during polishing, the amount and type of coating applied or the quality of the substrate. Many industries measure gloss to ensure the quality of their products.

Most paints and coatings are gloss controlled from formulation, checked regularly during manufacture and finally during application. Changes in gloss levels anywhere in this process can lead to substantial visual differences in batches offered to the end user. Closely controlling gloss means products are produced with maximum visual impact and rejections are avoided. The protective coating industry monitors gloss during the lifetime of a coating because as the paint ages its gloss level drops. When it reaches a preset level the structure is re-painted ensuring that a maximum lifespan is achieved from the coating without the risk of corroding the structure it protects.