How Gloss Effects Paint Color Perception

An object’s glossiness greatly affects the way our eyes perceive size. Compare any object – a ball for example – and look at a glossy one versus one with a matte finish. Which looks more three-dimensional? Most people would vote for the glossy ball – and there’s a scientific reason behind it.
Objects take light and change or absorb it. Colorants in dye or pigment will selectively absorb some wavelengths of the incoming light while transmitting or reflecting other wavelengths. The amount of light that can be reflected or transmitted at each wavelength can be calibrated; this is the “spectral curve of the object’s color characteristics.”
For matte objects, most of the “incident light” is reflected. Color is then seen in the diffuse reflection, and gloss is seen in the specular reflection. The specular angle reflection is, in general, the greatest amount of light reflected at any single angle. But specular reflection only takes into account 4% of total reflected light. The leftover reflection is in the diffuse reflection.
If you take two objects that are exactly the same color, but whose surface characteristics are different, the color you perceive for each is different. Objects with a glossy exterior appear darker and very chromatic. On the opposite end of that, matte finishes appear lighter and less chromatic.
Titanium dioxide and additional white pigments “opacify paint films primarily by diffusely reflecting light.” The reflection happens because the white pigment will bend or scatter light easily. If a paint film has enough white pigment, almost all visible light hitting it (excluding a tiny amount that is absorbed by a pigment or vehicle) will be reflected; then, the film looks to be white, opaque, and bright.

The main control of brightness and opacity in white paint films depends solely on the scattering of light; this basically means the bending of light, and in coatings, light can be bent by surface refraction, reflection, and diffraction.
If light hits a single high (relevant to the surrounding vehicle) “refractive index transparent particle,” the part that isn’t reflected goes into the particle and changes from its original journey. As light goes into a medium of higher refractive index, it becomes bent toward a line drawn perpendicular to the surface at the entry point. When the light goes out, it’s bent away from the perpendicular. The larger the difference in refractive index between the medium and the particle, the more the light will bend. Thus, the angle of reflectance is a vital component in evaluating color and gloss.
If you’re color matching, consider the angle that you’re viewing the color from and the light source. A good tool to use is a color spectrophotometer. A color spectrophotometer is used to measure transmitted or light or the intensity or transmitted light as a function, wavelength, or color. These tools are useful in many situations; i.e., measuring the quantity of light absorbed by a medium that the light is entering and leaving. Spectrophotometers can also be used to measure the amount of light which is reflected by an object (these are known as reflectance spectrophotometers).

Spectrophotometers measure two major classes of measurement, called single and double beam. Single beam spectrophotometers measure the change “in the intensity of a single light path through a medium.” Double Beam spectrophotometers will look at the light intensity of two separate light paths; it then figures out a ratio.
Color spectrophotometers are relatively easy to use and are available as remote mounted, hand-sized, desktop, or a full system integrated unit. Many industries use spectrophotometers, like the aerospace, pharmaceutical, material manufacturing, pulp or paper, building materials, food, glass, chemical, paint or coatings, or plastics industry.
In our house painting terms, we can deduce that paints with a glossy finish could potentially make a room seem bigger; however, it could also highlight surface imperfections. On the opposite end, paint with a matte finish covers more easily, but may not aid in making a room appear larger. Glossy paints also tend to cost a bit more. In the end, it is up to the prudent to make the decision in gloss vs. matte, large vs. small.