Hiding power is one of paint’s most important attributes. If a paint doesn’t effectively hide the surface beneath it, its color won’t come through as intended and the finish won’t look good. On a more detailed level, the hiding power of pigments within the paint must be enough to cover the solution’s substrate.
Paint’s three main components – the pigment, solvent, and binder – all serve crucial functions, but only the first should be visible in the final product. Consequently, if you want to create or select the best paint for a job, you must consider the pigment’s hiding power.
Where Does the Hiding Power of Pigments Come From?
Choosing a paint with appropriate hiding power requires an understanding of where this power comes from. This is a more complex consideration than many may realize at first.
Color
The most obvious factor behind pigment hiding power is its color. You perceive color by what light wavelengths in the visible spectrum – between 380 and 700 nanometers – reflect off a surface back to your eyes. If a pigment absorbs all frequencies within this range, it comes across as black, and if it reflects everything, it appears white.
This reflection and absorption play a crucial role in hiding power. The pigments must absorb enough light to reflect desired wavelengths, but prevent light from reflecting off the substrate beneath it. If more light passes through the film and reflects off the substrate, you’ll see the underlying substrate more.
Because different colors reflect and absorb light differently, maintaining this balance is easier with some colors than others. However, it’s also important to recognize that absorption and reflection aren’t the only types of light scattering that affect perceived opacity.
Refraction and Diffraction
There are four different types of light scattering. Absorption and reflection are what primarily dictate perceived color, but refraction and diffraction make an impact, too. While these may not change colors as dramatically, they play an important role in hiding power.
Refraction happens when a light wavelength changes path after passing through a particle. Diffraction also changes light’s direction but occurs when light bounces off a particle’s edge instead of passing through it. Both phenomena can stop light from reaching a substrate beneath a film, so they’re essential for hiding power.
The more diffraction and refraction a pigment gives you, the better. This scattering can result in bolder colors, but more importantly, it will minimize how much you can see of the underlying substrate.
Paint Quality
Light scattering in all its forms is the most critical factor in pigment hiding power, but not the only one. The quality of the paint mixture also impacts the final effect, largely by how well it capitalizes on the scattering qualities of different pigments.
There are five general types of pigments in paint – primary white, color, extender, metallic, and specialty. Some people group whites and colors together as simply “primary pigments,” and you may classify metallic pigments as “specialty.” Each category serves a different role in the film’s final appearance, and balancing each one gives you more options for boosting hiding power.
If your primary white has high scattering properties, you can afford to use a less powerful color pigment. Similarly, highly reflective metallic pigments can compensate for colorants and whites that let more light pass through. Making the most of these ratios in your mix helps achieve optimal hiding power.
Application Thickness
You can also improve the hiding power of your paint by applying it in thicker layers. This strategy doesn’t technically make your pigments’ hiding power stronger, but it produces the same result.
Creating a thicker consistency in your paint through more pigments or more viscous substrates can boost opacity but may make the application more difficult. The easier alternative is to apply the paint in multiple layers, allowing the light scattering of each pigment layer to multiply each other’s effects.
Optimizing Pigment Hiding Power
Once you know how these various factors impact pigment hiding power, you can take more control over maximizing it. Because perceived opacity comes from so many different steps, you can take several approaches to optimizing it for your needs.
Test Pigments’ Contrast Ratio
One of the most important steps in maximizing the hiding power of pigments is to test their contrast ratio. These tests will help you determine the felt effects of your pigments’ light scattering properties.
Contrast ratio measures the difference between a pigment’s apparent reflectance against a white background and that against a black one. Usually, you’ll paint an area spreading across a black and white background. If the color appears the same in both sections, it has high hiding power, and if not, its opacity is weak.
You can notice large differences with the naked eye, but it’s best to use a spectrophotometer or opacimeter to measure them. On top of providing more precise measurements, spectrophotometers can measure both visible wavelengths and ultraviolet light, offering insight you can’t get by yourself.
Consider All Pigments
Another best practice is to think outside of the realm of your primary pigment. You want the hue of your primary colorant to come through the most, so in that aspect, it’s the most important, but working with different secondary pigment ratios can make a big difference.
Using a colored base may seem like the best way for your desired hue to be bold, but that’s not necessarily the case. A stronger white base like titanium oxide may yield a better result for less money. While it doesn’t technically add to the color of your primary pigment, it improves its hiding power, making it seem bolder.
Use Full-Spectrum Paint
One often overlooked method to optimize pigment hiding power is to use full-spectrum paints. These solutions include pigments from across the visible light spectrum, whereas most conventional paints only use a combination of two to three colors.
Full-spectrum paint does cost more to produce because it contains more pigments, but you need less of it to achieve the same effect. More pigments equal more light scattering, improving your hiding power without having to rely on black pigments, which can desaturate your paint’s final color.
Use Finer-Gound Pigments
Similarly, you can use more finely ground pigments instead of coarser ones. Coarse-ground pigments are more affordable, but like with full-spectrum paint, the more costly alternative may be cheaper in the long run when you consider its application.
Individual large pigment particles may block more light than smaller ones, but smaller ones scatter light in more directions on a large scale. Consequently, using a finer grind results in better hiding power in fewer coats.
You Can Impact Pigments’ Hiding Power in Many Ways
The hiding power of pigments is a crucial consideration in creating or selecting the right paint. When you know what influences these characteristics and how to capitalize on them, you can make the most cost-effective decisions.
Paint quality is a more complex consideration than it may seem. However, this means you have more options to control it than it initially appears, so you can use these many factors to your advantage.
