Glossiness is a physical property that measures how well a surface can reflect light under a certain set of geometric conditions. So, it shows the property of reflection with direction selection. Glossiness is an important optical index because it shows how well the surface of an object can reflect light. Gu is usually used to measure how shiny something is.
Glossiness can be measured in many ways, but the most common way is with a glossiness meter. It is made up of a light source, a receiver, a standard plate, and other parts. The black glass that was used to measure the gloss has a refractive index of NP = 1.567.
Assuming that its plane is perfectly polished, it will reflect the natural beam. At this point, the gloss value is 100.0 gloss units. Then, just like before, the amount of light that the object’s surface reflects is divided by the amount that a standard plate reflects. This tells the relative value of how shiny the surface of the object is.
A gloss meter is a special tool for measuring the shine on the surface of things like ceramic, paint, ink, plastic, marble, aluminum, hardware, and other coatings. It is a tool for controlling the shine of a product’s surface. In general, testing can be done at 20, 60, or 85 degrees. What’s the difference between different angles?
What’s the difference between tests done with a glossometer at different angles?
At the moment, most gloss meters on the market have three main angles for measuring: 20°, 60°, and 85°. Different measuring angles work for surfaces with different levels of shine. Angles of 45° and 75° will also be used to measure things in the paper industry and in other fields.
The 75° gloss method is mostly used for coated paper and paperboard, uncoated paper and paperboard, and paper and paperboard samples with low printing gloss.
The 20° gloss method is most often used to measure high gloss paper and paperboard, such as cast coated paper, wax gloss paper, and polishing paper, as well as high gloss printing paper and paperboard samples, high gloss ink and paint, and so on.
Most of the time, the 45° gloss measurement method is used to figure out the gloss of aluminum foil paper, vacuum aluminized paper, and other high-gloss metal-composite papers and paperboards.
The 60-degree gloss method is mostly used to measure all kinds of paper, coatings, paint, and other materials. The 85° gloss method is mostly used to measure coatings, low-gloss paints, and other things like that.
How to choose?
For different object surfaces, the suitable measurement angle is also different.
- General materials can be measured by 60° gloss meter.
- For high-gloss materials, a 20° gloss metercan be selected.
- For low-gloss materials, an 85-degree gloss metercan be selected.
If the glossiness of the object surface is uncertain, it can be detected by a triangulation glossiness instrument.
Each range is easy to measure with its own angle. It is best to start with an angle of 60° to figure out which angle is best for measuring. The coating is called semi-gloss if the result is between 10 and 70 gu, which is easy to measure with this angle. If the result is less than 10 gu, the product has low gloss and should be measured at 85°. If the result is more than 70 gu, the product has a high gloss and is easy to measure at 20 °.
You can’t use the above method to compare the difference in gloss between two samples. You can only choose the same angle to measure. Different angles give different values for how shiny something is. If the angles used to measure are different, it is impossible to compare the results.
How a gloss meter works to measure
Through the lens L1, the light source g sends a beam of light to the measured surface P. The measured surface P then bounces the light back to the lens L2. The beam is focused on the photocell on the optical cable B by the lens L2. After photoelectric conversion, the photocell sends the electrical signal to the processing circuit for processing. The instrument then shows the measurement results. The amount of shine. JIS says that a percent or a number is the unit of glossiness.
What is the difference between roughness and gloss?
- Roughness refers to the micro-geometric characteristics composed of small spacing and peak valleys on the machined surface.
- Glossiness is a physical quantity that evaluates the ability of a material surface to reflect light under a set of geometrically specified conditions.
- Surface roughness is closely related to mechanical parts’ matching properties, wear resistance, fatigue strength, contact stiffness, vibration, and noise.
- Gloss, as the surface characteristic of an object, depends on the specular reflection ability of the surface to light. So-called “specular reflection” refers to the reflection phenomenon where the reflection angle is equal to the incident angle.
- Roughness has an important impact on the service life and reliability of mechanical products.
- The greater the incident angle, the greater the specular reflectance, and the higher the gloss. That is why high-gloss materials should be measured with a high-gloss meterat a 20-degree angle. On the contrary, the lower the specular reflectance, the lower the gloss.
Price of portable glossometer
A portable glossometer can cost anywhere from $100 to $2000, so when we buy one, we need to compare prices carefully. Most gloss meters on the market have a testing range of between 100 and 1000 gu. In general, the price is lower when the range is smaller and higher when the range is larger.
People say that when you buy a glossiness meter, you shouldn’t just look at the price. Some glossiness meters are cheap and might not have the technology they need. Maybe the same sample is tested more than once, and each time the results are very different.
The BYK glossometer gives accurate test results, but the price is very high. A single-angle glossometer costs about $2,000 in the United States. The high-quality glossometer made in China has a range of 200 gu. The test data matches the comparison data from BYK, but the price is around $1,000. It is both inexpensive and useful.
Compared to the different parameters of the instrument, this is the main way to decide whether or not to buy a gloss time. The price can only be used as a guide, and it can’t be the main reason for buying something. Choosing the right glossometer is very important.
- The glossometer has two working plates: one for high light and one for medium light (or low light). In the daily measurement, which plate is used to set the glossometer?
The gloss meter should be set up with a high-gloss plate, and after that, the measurement can be done. If the medium light (or low light) plate is used to adjust, it will often lead to a large measurement error. Please give this your full attention.
- What is the purpose of a working board with medium (or low) light?
Most of the time, a white ceramic plate is used to calibrate instruments as a medium-light (or low-light) working plate. Calibration is the process of making sure that the working board and the instrument are in the right place by putting the instrument on the medium light (or low light) board after it has been adjusted on the high light board (usually black glass).
Most of the time, the instrument is calibrated after it has been used for a while or when there are doubts about the results of a measurement. Calibration does not have to be done before every measurement. Because of how the working plate and instrument were used and stored, the surface of the working plate and the lens of the instrument are stained or worn, which makes the measurement very inaccurate. By checking, we can find problems early and fix them so that they don’t cause problems in the operation.
- During the check, it was discovered that the gloss levels of the two working plates did not match. What’s going on? How do we fix it?
When something goes wrong with a newly bought gloss meter, it’s often because the two working plates aren’t clean. Please wipe the surface of the working plate gently with an absolute ethanol-soaked soft cloth or medical cotton ball.
If the instrument has been used for a while, repeat the steps above to get rid of the problem of board surface contamination. If the problem keeps happening, check to see if the instrument has a sign of low voltage, which can cause strange behavior. Also, the gloss value of the working board has changed, which means that it needs to be calibrated again.
- What does the symbol Gs () mean?
Gs () is a symbol for the physical amount of glossiness, which is the angle of light that hits the surface, like 60° or 90°. The English word for gloss unit is “gu,” which is short for “gloss unit.”
- The glossometer is not stable, and the reading changes quickly after it is set. Why?
Most of the time, the following are the reasons:
(a) The battery is about to die, which means that the voltage is too low. Right now, there isn’t enough power to make the instrument work normally.
- b) The measuring area is damp and occasionally cold or hot (there is a wide temperature range).
In the measuring port of the instrument, water mist covers the lens surface or working plate surface.
(c) Strong light from outside comes in through the measuring port while measuring or calibrating, which makes it hard to measure or calibrate.
After starting the machine, the user should wait a few minutes, then adjust and measure once the circuit has stabilized and warmed up. This makes it possible for the user to get very accurate measurements.
- Is it true that the glossier a surface is, the brighter it is?
In general, under the same conditions for measuring, the gloss value shows how bright the surface of an object is. But when measured from different angles, the gloss value will be different. So, the only way to compare glossiness values is to use the same glossiness instrument under the same set of conditions.
If the measuring tool and angle are different, the values for glossiness can’t be compared. So, if a user wants to check the shine of a product, they have to use the same gloss meter and measure it from the angle given.
- What are the benefits of the glossometer’s function that takes temperature into account?
Because the luminous efficiency of LED light sources changes with the ambient temperature, especially in autumn and winter when the temperature difference between morning and evening and indoor and outdoor is very large, when the ambient temperature of the glossometer changes, the instrument will automatically adjust the luminous effect of the light source to match the new temperature so that the test data won’t be wrong. Once the instrument has been calibrated at a certain temperature, it can be tested to see whether or not the temperature changes.
- How does gloss change the color?
When light hits an object, the object’s surface will have both specular and diffuse reflection. The specular reflection of light is stronger than the diffuse reflection on a surface with a high gloss, which means that the specular reflection is strong. In the same way, the diffuse reflection is stronger on the low-gloss surfaces of things.
So, the sample above shows that when it is smooth, the color is brighter and the chrome is higher, but when it is rough, the sample is not as bright. A specular reflection is easy to overlook when looking at the color of things in everyday life, but a color difference meter makes it easy to notice. But we shouldn’t ignore the interference of specular reflection when we look at the reasons why colors change.
- How do I choose between the 60-degree gloss meter’s different apertures?
There are three different kinds of small-holed gloss meters with angles of 60°, 45°, and 20°. The most common type is the one with an angle of 60°, which has 1.5 mm x 3 mm and 3 mm x 6 mm holes. The 1.5mm x 3mm opening can be used to measure small planes and curved circular tubes. With a small plane and a large radian, a 3mm x 6mm hole can be used to measure cylindrical physics. The measuring plane can work with a hole that is 14 mm x 28 mm.