Measuring gloss levels is an essential part of quality control and a product’s visual appeal for many applications, from automotive paintwork to wooden flooring. Ensuring consistent and uniform gloss or shine of a surface is determined by using a specialised instrument called a gloss meter.
Gloss levels can vary significantly, so let’s discover how a gloss meter can provide an objective way to assess the quality of high gloss, semi-gloss, and low-gloss surfaces.
What is gloss?
Before we start glossing over gloss meters, it’s best we define what gloss is. Gloss is a visual characteristic that refers to the reflective or shiny quality of a surface. This ability of a surface to reflect light in a specular (mirror-like) way can be observed in a wide range of materials, including ceramics, metals, and plastics.
How is gloss measured?
Gloss is measured by projecting a light beam at a fixed angle and intensity onto the surface being measured and the amount of reflected light at an equal but opposite angle.
What is a gloss meter?
A gloss meter is an optical measuring instrument that measures the specular reflection of a surface (gloss level) of a surface. It provides quantifiable gloss measurements, expressed as gloss units (GU).
Gloss meters can be used to measure the gloss of a wide range of different surfaces, with different geometries available for each. For non-metal materials such as inks, paints and plastics, the amount of light reflected increases with the angle of illumination and is either diffusely scattered depending on its colour or some of the light is absorbed into the surface. Metals tend to be more reflective, making them less sensitive to different angles of measurement.
How to use a gloss meter
Classic gloss meters are designed for gloss measurement on flat surfaces. They typically consist of a fixed mechanical assembly consisting of a standardised light source that emits a parallel beam of light onto the test surface to be measured and a filtered detector located to receive the rays reflected from the surface.
Before you begin using your gloss meter, ensure it’s calibrated to guarantee the quality of your gloss measurements. You then need to select the appropriate measurement angle.
The three common gloss measurement angles are 20°, 60°, and 85°, with each angle suited to different gloss levels and covering most industries coatings applications. Always start with a glossmeter set at a 60° angle of incidence and use the table below as a guide.
Gloss Range
60° Value
Notes
High Gloss
>70 GU
If measurement exceeds 70 GU, change test setup to 20°
Medium Gloss
10 - 70 GU
60°
Low Gloss
<10 GU
If measurement is less than 10 GU, change test setup to 85°
In addition to the angles above, 45° is used for the gloss measurement of plastic films, ceramics, anodised aluminium, and textiles, whereas 75° is the go-to for measurement of paper and paper products.
Once you’ve established the appropriate measurement angle, place the gloss meter on the surface, and take a reading by pressing the button.
Glossmeter light reflection.
Interpreting your gloss meter readings
To understand your gloss meter readings, it’s important to remember the unit of measurement for gloss is the Gloss Unit (GU). The GU is a scaling based on a polished black highly reflective gloss standard with a defined refractive index having a specular reference of 100 GU at the angle specified. This gloss standard is used to establish the upper range of the glossmeter, while a perfectly matt surface would be 0 GU.
This scaling works well for most non-metallic surfaces and coatings as they normally fall within this range. For other more reflective materials such as polished metals and mirrors, a scale of up to 2000 GU can be achieved using a mirror gloss standard.
Benefits of using a gloss level meter
Many gloss meters benefit from compact size and portability, making them practical for on-site inspections and fieldwork.
Enables the glossiness of various materials to be quickly, easily, objectively, and accurately assessed in real-time.
Reduces the reliance on subjective visual assessments.
Vital for ensuring quality control and consistency in gloss levels during the manufacturing process, particularly when maintaining the aesthetic appeal and quality of a product.
Understanding how different materials, formulations, and processes impact gloss is necessary for research and development, helping engineers and scientists innovate new products and enhance existing ones.
Manufacturers can ensure products meet specific gloss standards and contributes to customer satisfaction and loyalty. This is especially crucial in industries where aesthetic quality is a key factor in consumer choice.
What industries and applications use gloss measurement?
Gloss meters are an indispensable test instrument across many industries, where precise gloss levels are critical for product performance and customer satisfaction. Common gloss measurement applications include:
Achieving the desired print quality for printed materials from magazines to packaging.
Assessing the finish of painted surfaces on vehicles.
Assessing the gloss levels of ceramics and tiles, as this can drastically influence their appearance and suitability for specific applications.
Ensuring consistent gloss levels for electronic products with glossy surfaces, such as smartphones and tablets.
Furniture manufacturing, so finishes on wood, laminates, metals, and synthetics meet design specifications and quality standards.
Measuring the gloss of a paint film by gloss meter.
What gloss meter do I need?
First off, you need to identify the surface you wish to measure. Flat surfaces can be measured with a traditional gloss meter like the Novo-Gloss 60° gloss meter. Curved surfaces require specialised gloss meters. For example, the Novo-Curve 4 has specially designed optics for accurately measuring the gloss at 60° of curved surfaces and small areas.
Also consider the gloss range of the measured object and the measurement range of the gloss meter — please refer to the table earlier in this guide if you’re unsure.
Always use a calibrated gloss meter, as this ensures you’re recording accurate results that match a range of industry gloss measurement standards. Below is a comparison of standards to help you with your gloss measurement applications.
Why choose AML Instruments to add gloss to your gloss measurements?
While the human eye is comfortably the best optical instrument to assess gloss, the only way to ensure objective, gloss level measurement criteria is with a gloss measuring device.
All of AML Instruments’ gloss meters are manufactured in the UK, enabling you to measure reflections on matt or reflective surfaces, with easy reporting and data transfer via BlueTooth to optimise your gloss measurement accuracy.
