Gloss is a measurement of how well a surface reflects light in a specular (mirror-like) direction—how lustrous or shiny an object appears. Depending on whether a surface is smooth or rough, the light reflected may appear “high gloss” or “matte”, respectively. “Semi gloss” refers to a surface that falls in-between.
Measuring gloss during the manufacturing process can help identify process issues—maximizing consistency and improving overall quality. An important part of QA/QC programs, gloss measurement contributes to improved manufacturing efficiency.
The durable PosiTector GLS Gloss Meter, available in 3 models, can measure up to 3 measurement angles to suit any application. The PosiTector GLS 20/60 and 20/60/85 are capable of calculating haze.
Conforms to ASTM C584/D523/D4039, ISO 2813/7668, DIN 67530, JIS Z 8741, AS/NZS 1580.602.2.
Gloss is an optical property that indicates how well a surface reflects light in a specular (mirror-like direction)—how shiny or lustrous an object appears. On high gloss surfaces, light is reflected at the angle of incidence (specular reflection), but on matte surfaces, the reflected light is scattered (diffuse reflection).
To learn more about gloss, read, "Measuring Gloss with the PosiTector GLS Gloss Meter".
Reflectance is the measurement of the amount of light detected versus the amount of light emitted and is expressed as a percentage. Some light waves are absorbed into the coating while others are reflected. The amount of light reflected is used to calculate gloss.
Some gloss meters, like the PosiTector GLS Gloss Meter can display both Gloss Units and Percent Reflectance (% Reflectance).
Haze is the appearance of a milky halo or bloom perceived in reflective surfaces due to microscopic imperfections in the coatings surface. The reflection from high gloss surfaces should be crisp but surface imperfections will tend to scatter the light producing a hazy appearance.
Gloss meters such as the PosiTector GLS 20°/60° and GLS 20°/60°/85° can calculate Haze Index in accordance with ASTM D4039 by subtracting the 20° from the 60° specular gloss measurements.
Gloss, Percent Reflectance, and Haze are measured using a digital gloss meter like the PosiTector GLS. The meter uses a calibrated light source and a light sensor at opposite, specular angles. Percent Reflectance is measured by comparing the amount of light sent versus the amount of light received. Gloss is then calculated automatically.
Depending on the application or gloss type, gloss meters include one or more measurement geometries—typically 20°, 60°, 85°, or a combination of these measurement angles (geometries).
The PosiTector GLS Gloss Meter is available in three models.
To determine the correct geometry for measuring a particular gloss application, it is common to begin with the 60° measurement angle. Based on that measurement, the appropriate angle can be determined.
Finishes that read greater than 70 G.U. at the 60° measurement angle are considered high-gloss and should be measured using the 20° measurement angle. High gloss coatings are typically seen on automobiles and other consumer products.
Finishes that read lower than 10 G.U. at the 60° measurement angle are considered matte and should be measured using the 85° measurement angle. Matte finishes are typically seen on fabrics, leathers, and military assets.
Finishes that read between 10 and 70 G.U. at the 60° measurement angle are considered semi-gloss and should continue to be measured using the 60° measurement angle.
The following standards are frequently used to determine gloss levels.
This test method covers the determination of 60° specular gloss of glazed ceramic whitewares and related products.
Refer to ASTM C584 for a complete description of the test method
This test method covers the measurement of specular gloss of nonmetallic specimens for gloss meter geometries of 20°, 60°, and 85°.
Refer to ASTM D523 for a complete description of the test method
The test method describes a procedure for using two specular gloss measurements to obtain a haze index for high-gloss nonmetallic specimens. It is particularly useful for evaluating the haze in clear finishes on nonglossy substrates, and the haze in reflected images produced by the surfaces of opaque glossy pigmented surfaces.
Refer to ASTM D4039 for a complete description of the test method
This International Standard specifies a method for determining the gloss of coatings using 20°, 60°, and 85° geometries. The method is suitable for the gloss measurement of non-textured coatings on plane, opaque substrates.
Refer to ISO 2813 for a complete description of the test method
This International Standard specifies methods for measurement of specular reflectance and specular gloss of flat samples of anodized aluminum using geometries of 20° (Method A), 45° (Method B), 60° (Method C), and 85° (Method D); and of specular reflectance by an additional 45° method (Method E) employing a narrow acceptance angle. The methods described are intended mainly for use with clear anodized surfaces. They can be used with colour-anodized aluminum, but only with similar colours.
Refer to ISO 7668 for a complete description of the test method
International Standard for using a reflectometer to assess the specular gloss properties of smooth-painted and plastic surfaces. (This standard has been replaced by ISO 2813.)
Refer to DIN 67530 for a complete description of the test method
This Japanese Industrial Standard specifies the methods of measurement for specular glossiness of the macroscopically smooth surface of product of mining and manufacturing industry.
Refer to JIS Z 8741 for a complete description of the test method
This International Standard is one of a series of standards dealing with the sampling and testing of paints, varnishes, and related products. It specifies a test method for determining the specular gloss of paint films using a reflectometer geometry of 20°, 60°, 85°. The method is not suitable for the measurement of the gloss of metallic paints. Identical to, and reproduced from, ISO 2813.
Refer to AS/NZS 1580.602.2 for a complete description of the test method