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Matting in Paints and Coatings - All You Need To Know

What is Matting Effect?

Matting is a property of coatings that delivers a smooth, subtle look and shows little-to-no sheen. Matting lowers the gloss/sheen by scattering the light in many directions leading to surface appearance less glossy.

Matt coatings are used to obtain a less glossy surface depending on the application. These coatings are widely used to coat substrates, such as wood, plastics, VCT, metals, etc. to:

Reduce glare & enhance appearance (aesthetic purpose), and
Hide surface imperfections (functional purpose)

There are several options to the coatings formulator to create a matt coating. Matting agents, such as silica, waxes and fillers are mixed with coatings and paints in order to impart a matt finish to the substrate. These include:

Matting agents when used with paints and coatings scatter the incoming light thus giving a matt effect to the desired surface. Moreover, the higher the dosing of matting agent in the paint, the stronger is the matting effect.

Several matting agents are available in the market depending upon their particle size and chemical composition and the best choice can be made depending on the application.

Let's explore how to obtain matt surface with different optical effects using various types of matting agents.

Optical Surface Modification to Obtain Matt Surface

In many cases, the surface of a coating or ink has to be altered to a different optical effect like a lower gloss or a certain texture. Reducing the gloss of a system is achieved by "destroying" the smooth surface of the glossy film, i.e. by introducing a kind of "micro-roughness". Surface roughness reduces the amount of specular reflected light, thus resulting in low gloss surface.

Optical Effect on Different Surfaces of an Object

Therefore, matting can be defined as a physiological-optical phenomenon produced by the surface of an object. It is subjective impressions that are identified by our senses.

Matting Agents – How Do They Work?

When a coating is applied to a substrate, the matting agent is uniformly distributed in the wet coating film. Upon the evaporation of solvents, they will extend beyond the film surface during the drying process due to film shrinkage, thus altering the film from a smooth and even - glossy - surface to a matt one.

This shrinkage is the main reason for creating (more or less) rough surface, or, in other words, a matted paint film. This shrinkage can vary from 30% to 60% of the wet film’s volume depending on the formulation’s volume solids.

Effect of Matting Agent on Coatings

Film surface micro-roughness is created by:

Film shrinkage/volume reduction
Size and number of matting agent particles
Orientation of the particles
State of dispersion
Interactions with other components, e.g. surfactants, catalysts, etc.

It is important to note that conventional coatings are relatively easy to matt because the film shrinks upon hardening due to emissions, but solvent-free and 100% solid systems, such as radiation-curable coatings, powder coatings, etc. are difficult to matt.