A glossmeter is a tool used to quantify the glossiness or shine of a surface. This device measures specular reflection, or the amount of light reflected off a surface. The glossmeter relies on gloss units (GU) to express degrees of gloss and shine. This unit is based on a reference measurement using black glass, which has a GU of 100. The higher this value, the higher the gloss of the surface being measured, with values in the thousands possible on high-gloss materials.
The average glossmeter fits into the palm of the hand, and is comparable in size to a calculator or smartphone. It includes a light source, which can be applied to the surface during measurement to create a fixed lighting condition. The glossmeter also includes an optical sensor that's used to calculate specular reflection. A display screen on the device provides the GU of the surface. Different glossmeters are designed for specific projects and applications, and may not be suited to all jobs.
When measuring the shine of a surface, the angle of the glossmeter can greatly influence readings. For high-gloss surfaces, the meter should be held at a shallow angle to the material. Medium-gloss finishes require a medium angle, generally ranging between 50 and 70 degrees. Low-gloss applications generally provide the greatest level of accuracy when the meter is held at a sharp angle to the surface. Metals tend to be less angle dependent than other materials, and some products, like plastic or vinyl, have fixed industry-specific illumination angles.
These tools can be used to measure everything from automotive finishes to furniture. They may also be applied to printings and paper, as well as plastic or specialty coatings. The glossmeter may also be used to measure the shine of building materials and finishes within a completed construction project.
For a basic example of the glossmeter and its benefits, consider marble or stone flooring projects. These surfaces are often polished to a high-gloss shine to bring out their natural color and beauty. This meter can be used to test a newly-installed marble floor to determine if it meets the project specifications. It can also be used to measure gloss on an existing stone floor to show homeowners the potential benefits of floor refinishing or restoration. By taking a second glossmeter reading after the restoration is complete, the contractor can provide measurable data on the improvement in floor shine or gloss.