1) What is Gloss ?
Gloss is an aspect of the visual perception of objects.
Gloss is the attribute of surfaces that causes them to have shiny or lustrous, metallic or mat appearances.
Gloss is a visual impression that is caused when a surface is evaluated. The more direct light
is reflected, the more obvious will be the impression of gloss.
Gloss effects are based on the interaction of light with the physical properties of the sample surface.
The other influencing component is the physiological evaluation scale. The human eye is still the best tool
to evaluate gloss differences. However, the visual surface control is insufficient, because evaluation
conditions are not clearly defined, and people see and judge differently.
In addition, the subjective perception of appearance is dependent on the personal experience: what
is glossy for a paper manufacturer might be dull for an automotive maker. Gloss is measured by focusing
on the reflected image and not by focusing on the surface. Eyesight and mood have a decisive role in
the visual judgment. Also, important is what our eye is focused on. We evaluate a surface by focusing
our eye on a reflected image of a light source. In order to guarantee a reliable and practical quality
assurance it is necessary to define appearance with objective, measurable criteria. Accurate
characterization of appearance does not only help to control quality, but improves quality and optimizes
Smooth and highly polished surfaces reflect images distinctly. The incident light is directly reflected
on the surface, i.e. only in the main direction of reflection. The angle of incidence is equal to the angle
Mat to Semi Gloss
On rough surfaces the light is diffusely scattered in all directions. The image forming qualities are
diminished: A reflected object does no longer appear brilliant, but blurred.
The more uniform the light is scattered, the less intense is the reflection in the main direction and
the duller the surface will appear.
2) What difference in gloss can a human see ?
If two different coatings are measured, what number of gloss units would be detectable by the
human eye, how many units would be perceived as significantly different?
When measuring at 60 Degrees these detectable differences depend on the gloss level of the
sample, for instance 3.0 GU difference measured on a very matte surface (perhaps 5GU), would be
seen by the human eye but on a higher gloss coating (perhaps 60 GU) the difference would be
very difficult to notice.
The only way that you can determine tolerances for your products would be experimentally,
perhaps preparing printed samples at different gloss levels that you can show to end users of
your coatings or internal "experts".
The other option is to change to a 20/60/85 degree instrument, the 85 degree glossmeter is
more sensitive to differences in gloss below 10 GU @ 60° and the 20 Degrees has higher
resolution on high gloss coatings (above 70 GU @ 60°). The advantage of using the three
angles is that there is more equality to the gloss differences, in our experience a gloss
difference of 5 GU, when measured with the correct geometry is just visible to a
3) Why Measure Gloss ?
Gloss is an aspect of the visual perception of objects that is as important as color when
considering the psychological impact of products on a consumer. In other words, "Gloss Sells"
Gloss has been defined as the attribute of a surfaces that causes it to have a shiny or
lustrous, metallic appearance.
The gloss of a surface can be greatly influenced by a number of factors, for example
the smoothness achieved during polishing, the amount and type of coating applied or the
quality of the substrate. Manufacturers design their products to have maximum appeal.
Such examples are; highly reflective car body panels, glossy magazine covers or satin
black designer furniture. Now what happens when products all of a sudden look different?
Customers see this as a defect, or poor quality. Using a glossmeter and having good quality
control practices eliminates this variable as a problem.
It is important therefore that gloss levels be consistent on every product or across
different batches of products. Gloss can also be a measure of the quality of a surface,
for instance a drop in the gloss of a coated surface may indicate problems with its
cure- leading to other failures such as poor adhesion or lack of protection for
the coated surface.
It is for these reasons that many manufacturing industries monitor the gloss of their
products, from cars, printing and furniture to food, pharmaceuticals and consumer electronics.
We also have Gloss Sensors used in process for real time gloss measurement. Please call us
at 1-866-462-6832 to discuss the inline application.