This standard outlines a method to evaluate low-angle glare produced by clear coatings on wooden furniture through an 80° glossmeter. It enables precise quantification of specular reflection, facilitating manufacturers, inspectors, and designers in assessing visual comfort and finish quality, especially in glare-sensitive settings like educational and assembly spaces.
Overview
This standard outlines a method to evaluate low-angle glare produced by clear coatings on wooden furniture through an 80° glossmeter. It enables precise quantification of specular reflection, facilitating manufacturers, inspectors, and designers in assessing visual comfort and finish quality, especially in glare-sensitive settings like educational and assembly spaces.
Audience
Contents
Structure
This section introduces the purpose of measuring low-angle glare (specular reflection) from transparent finishes on wooden furniture, emphasizing its importance in brightly lit areas such as schools and auditoriums. It details the quantitative expression of glare as a percentage reflection and references its derivation from British standards, aligned with international and Indian norms. It also lists related parts of the series focusing on durability and marking resistances. The clause on mutual agreement between buyer and seller for test conditions and the protocol for reporting mean glare values are covered. A formula for calculating mean reflection percentages is provided along with a flowchart illustrating the testing sequence. The standard ensures glare quantification to prevent visual discomfort in illuminated environments.
Defines the scope as the measurement of low-angle specular reflection from clear coatings on wooden furniture surfaces. The results are given quantitatively as percentage reflection under controlled test conditions, applicable to flat finished wood panels or furniture pieces. Key parameters include specifications of the light source, lens focal lengths, incident and receiving beam angles, lens diameters, photocell placements, and enclosure details. The optical setup is summarized with a schematic diagram explaining the collimated beam path and detection system. Notes on gloss standards, calibration, and equipment positioning are included to ensure repeatability and accuracy.
Details the apparatus specifications needed to perform the test, including the collimated light beam diameter of 16 mm, lens focal lengths of 31 ± 1 mm for both incident and receiving optics, and the precise positioning of the light source along the optical axis. The incident and receiving beam angles are set at 80° to the surface normal, with slight adjustability. The photocell is positioned 50 mm from the receiving lens with a diameter equal to or larger than the lens diameter, enclosed in a blackened tubular container to minimize stray light. A constant voltage power supply is necessary for the search unit operation. An optical path diagram illustrates the light source, lenses, test surface, and photocell arrangement to ensure precise measurement of low-angle glare.
Describes the setup of the photoelectric glossmeter, where incident and reflected beams form an 80° angle with the surface normal and the photocell lies in the same plane. The galvanometer connected to the photocell is scaled from 0 to 100 units, with full scale set using a gloss standard. The gloss standard is a highly polished clear glass with stringent flatness and refractive index requirements, sized to fit the instrument base and blackened on edges to prevent stray reflections. The calibration procedure involves placing the instrument on the standard, adjusting for maximum galvanometer deflection, and setting the scale to 100 units. The gloss of test surfaces is reported relative to this standard. A flowchart depicts the calibration and measurement process ensuring consistent gloss readings.
Specifies the preparation protocol for test surfaces, including application of the complete finishing system per IS 2338 (Part 1) on a flat wooden substrate sufficiently large to accommodate the glossmeter search unit. The final coating must be conditioned for at least 28 days at 27 ± 2°C temperature and 65 ± 5% relative humidity with free air circulation, unless mutually agreed otherwise. For matte finishes achieved through abrasion, testing is conducted on the completed item. Measurements are taken at six representative locations with the measurement plane aligned parallel to the wood grain. A summary table consolidates these parameters, and a flowchart illustrates the sequence from substrate preparation to measurement.
Outlines the test procedure focusing on aging conditions for the final coat (27 ± 2°C, 65 ± 5% RH, minimum 28 days), with allowance for reduced aging if agreed. Calibration of the glossmeter against a gloss standard with a value of 100 units is mandatory. The test involves measuring gloss or low-angle glare on the prepared surface, ensuring the instrument is correctly positioned and readings are taken as per specifications. The gloss calibration table shows acceptable gloss unit ranges for different glass types used as standards. A flowchart details the process from surface preparation through calibration to measurement validation, ensuring reliable and repeatable results.
Describes the reporting requirements, emphasizing the need to record each individual measurement taken both along and across the wood grain. Mean values for each direction should be computed using the specified formula (arithmetic mean). Reports must include individual readings and averages, with all values referenced to the calibrated gloss standard (100 units). The test conditions agreement between purchaser and supplier should be noted. A table provides a format for presenting results, and this approach promotes clarity and uniformity in documenting the finish gloss or glare characteristics.
Frequently Asked
The standard specifies a photoelectric glossmeter designed to measure low-angle glare characterized by: a search unit emitting a collimated light beam at an 80° angle relative to the surface normal; a photocell positioned to receive reflected light also at 80° in the same plane; and a galvanometer with a 0 to 100 unit scale calibrated using a highly polished plane glass reference. The gloss of the test surface is expressed as a percentage relative to this standard, ensuring precise low-angle glare evaluation on wooden finishes.
The test surface should be prepared by applying the full finishing system as per relevant standards onto a flat wooden substrate. The final coat must be aged at 27 ± 2°C temperature and 65 ± 5% relative humidity for a minimum of 28 days, with free air circulation. For matte finishes achieved through abrasion, testing should be performed on the finished furniture. Before measurement, the glossmeter must be calibrated against a gloss standard set at 100 units. Measurements are taken at six representative areas with the instrument positioned flat and the measurement plane aligned parallel to the wood grain to assure accurate and repeatable results.
The gloss standard functions as a calibration benchmark for the glossmeter. It is a highly polished clear glass with strict flatness and refractive index specifications, sized to match the instrument base and treated to prevent stray light reflection. During calibration, the instrument is placed on the standard, the photocell angle is adjusted to maximize galvanometer deflection, and the galvanometer setting is fixed at 100 units. This process establishes a reference against which all test surface gloss measurements are expressed as a percentage, ensuring consistent and repeatable results.
Measurements are conducted in two orientations: first, with the vertical plane containing the incident and reflected beams aligned parallel to the wood grain direction; second, repeated with the same plane positioned perpendicular (at right angles) to the grain. Each set of readings is recorded separately, and mean values for both directions are calculated. This dual-orientation approach accounts for the anisotropic nature of wood, providing a comprehensive evaluation of gloss and glare characteristics.
The finish should be aged under controlled conditions comprising a temperature of 27 ± 2°C, relative humidity of 65 ± 5%, and free access to air for a minimum duration of 28 days. These conditions ensure the surface properties stabilize before testing. Adjustments to the aging duration are permitted if agreed upon by the purchaser and supplier. Additionally, if a matte finish is produced by abrasion, testing is performed on the completed furniture surface. Adhering to these parameters guarantees reliable and consistent glare measurement outcomes.
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