Measure gloss with a PosiTector GLS gloss meter

Consumers love gloss – and this can be seen in nearly every industry, from automotive to electronics to baby toys. No matter the industry, gloss is often associated with luxury and wealth. Research suggests that humans' innate love of gloss may be based on a biological need for water: the shinier an object is, the more likely it is to "quench its thirst."

From an industry perspective, gloss can have a very specific purpose. Gloss, by definition, is an optical property that expresses the degree to which a surface reflects light in the direction of specular reflection (specular), or how glossy or glossy an object is. While many industries prefer a smoother finish, some require a matte finish.

Why measure gloss?

Measuring gloss as products are manufactured can improve production processes by identifying process issues, maximizing consistency, reducing waste and improving overall quality. Surface texture, coating properties and paint application all contribute to the appearance of the coating. While large differences in gloss are easily detectable by the human eye, such as comparing a matte finish on a military asset to a glossy red sports car, smaller differences in gloss can be harder to see but still have an impact on process control Tremendous influence.

What is reflectivity?

When light hits a surface, some of it is absorbed and some is reflected. Reflected light is responsible for how objects are perceived. The nature of the reflection is often related to the surface finish of the object. On a smooth, polished surface like a mirror, light is reflected at the opposite angle to the angle it arrived at; this is called "specular reflection." On a rough surface, light rays are reflected at all angles, and a relatively small amount of light is reflected at specular angles.

What is percent (%) reflectance?

Reflectance is a measure of how much light is detected versus how much light is sent, expressed as a percentage. Gloss meters such as the positive gel GLS can display GU and percent reflectance directly on the gage.

What is gloss value? What are Gloss Units?

According to ISO 2813, the gloss value is the ratio of the reflectance of the specimen to that of a standard polished black glass surface, "refractive index 1,567 in the specular direction, wavelength 587.6 nm", multiplied by 100. It is expressed in units of gloss.

What is Haze Index?

Haze is the perceived "milky" halo or flowery appearance of reflective surfaces caused by microscopic imperfections in surface texture. The haze index is calculated by ASTM D4039 and defined as the difference between the gloss values measured at 60° and 20°. The POSITector GLS 20/60 and 20/60/85 are able to calculate haze when selected in the settings menu.

How is gloss measured?

Digital gloss meters like the DeFelsko PosiTector GLS Gloss Meter use a calibrated light source and light sensor to measure surfaces at opposite specular angles. Reflectivity is determined by comparing the light energy emitted by the light source to the energy received by the sensor. Glossiness is then automatically calculated using a lookup table.

The PosiTector GLS Gloss Meter includes a reference standard built into the base of the device. When the device is turned on or selected from a menu, the instrument is automatically calibrated using a standard known gloss unit value.

Choose the best angle for gloss measurement

On most surfaces, reflectance and gloss values increase as the viewing angle increases. This is often obvious to the naked eye: for example, in the case below, there is barely noticeable reflectance when viewed from above, but when the same case is viewed from a wider angle (closer to the surface), there is visible reflectance. This phenomenon can be used to provide higher measurement resolution on glossy and matte finishes.

To determine the correct gloss measurement angle, first measure gloss at a 60° angle:

If the result is between 10–70 GU, the relevant object is considered semi-gloss and a measurement angle of 60° is appropriate.

If the result is greater than 70 GU, the surface is considered high gloss and should be measured at a 20° angle.

If the result is less than 10 GU, the surface is considered matte and should be measured at an 85° angle.

How to Take Gloss Readings with a GLS Gloss Meter

The PosiTector GLS Gloss Meter is available in three models:

GLS 60° is used to measure most gloss applications and is the angle of choice for semi-gloss

GLS 20°/60° for measuring high gloss to semi-gloss and calculating haze index

GLS 20°/60°/85° for measuring high, semi and matte gloss and calculating haze

Gloss measurement is fast and easy with the PosiTector GLS Gloss Meter:

1. The importance of keeping the calibration tiles clean to verify the accuracy of the meter cannot be overemphasized. The gloss standard should be cleaned with the included cleaning wipes periodically or whenever dirt or debris is visible. After a successful self-test, the positive GLS is ready for measurement.

2. Before turning on the power to the gage, make sure the protective backplate is securely attached to the probe. When power is applied and power-on calibration is enabled, the probe will automatically perform a self-test and calibration using the calibration standards contained in the protective backplane; traceable calibration certificates are included for both probe and gloss standards.

3. Remove the protective back plate from the probe and place the probe on a firm, flat surface. Simply press the button to read; the gage will beep twice and display the measurement.

Features of GLS Gloss Meter

PosiTector GLS has a variety of measurement modes and useful functions, making it suitable for almost any application:

HiLo mode: for quick checks or pass/fail checks

Differential Mode: Automatically calculates the difference between the current reading and the stored reference*

Normal Scan Mode: Measures and saves up to 120 readings per minute*

Statistics Scan Mode: Continuously measures and displays real-time statistics, saving each scan to memory*

Spare Calibration Standards: Store multiple calibration standards (tiles) for quick calibration adjustments

*Available only on PosiTector GLS premium models

As it is part of the PosiTector platform, the PosiTector GLS is compatible with any PosiTector probe; quickly convert from gloss gauges to coating Thickness Gauges, surface profile Thickness Gauges, environmental gauges and more. It also has the added benefit of a large 2.8-inch impact-resistant color touchscreen and easy-to-use menus. A great Thickness Gauge can be connected to a personal smart device or laptop via WiFi or Bluetooth.

Manage gloss measurement data with PosiSoft software

Once the gloss test is complete, download the readings using the built-in USB port or, if using an advanced gage body, via WiFi. Once connected, use PosiSoft desktop software to quickly and easily download, view and print stored readings in professional PDF reports. Fully customized reports can be created to match existing paper forms or layouts.

in conclusion

While gloss measurement is often done for aesthetic reasons, measuring gloss can have a significant impact on process and quality control. The PosiTector GLS Gloss Meter is fully featured to handle many gloss measurement applications.