Vinyl siding is offered in a variety of colors and looks that include imitation wood grains and brick finishes. In order to maintain consistent gloss on new and replacement siding it is very important to objectively measure gloss.The majority of vinyl siding is medium to low gloss with various structures. The heavy and random structuring of the material makes it difficult to obtain repeatable and reproducible readings with a glossmeter. Any structure or irregularity will cause scattering of the light being reflected back in the main direction of reflection (specular component). The deeper and more inconsistent the structure of a specimen, the less reproducible the gloss readings will be.

Due to the relatively low gloss of most vinyl siding, it is necessary to use a flat angle (as measured from the perpendicular) to quantify gloss. ASTM D 3679 "Specification for Rigid Poly Vinyl Chloride (PVC) Siding" recommends the 75° geometry and ASTM D523 "Test Method for Specular Gloss" advises the 85° geometry for measurement of low gloss material. The choice of measuring geometry will depend on your supplier's/customer's specification and on the specific application. Sometimes the 75° geometry will produce more repeatable and higher results on vinyl siding with very deep structures.

BYK-Gardner's micro-gloss glossmeters - available in single angle (20°, 45º, 60°, 75° or 85°) or three angle (micro-TRI-gloss) configurations - offer a practical and easy solution. To guarantee high reproducibility on heavily structured surfaces a larger surface area must be measured. To accomplish this, the micro-gloss can be used in 'continuous mode’, allowing continuous measurement of the surface. In this way, measurements can be recorded over as large of a surface area as desired, showing the maximum and minimum values, as well as the average and mean.  You can also use the statistics mode to automatically calculate the difference to your standards.

Documentation of quality control results is important, so each glossmeter also includes BYK-Gardner’s easy-link software, which allows direct transfer of all collected data to Excel®, with results shown immediately in a professional QC report.