Paint Viscosity: A Look at the Basics

by admin on June 10, 2013

When most people consider the paint they’ll use to give a home, vehicle, or other area a new look, they’re most often concerned simply with the color of the paint that they’re choosing. While the pure aesthetic value of the paint choice is important, as it represents the very reason for choosing paint in the first place, this should not be considered the only metric to measure before selecting a paint type, a brand of paint, and the method of application that will be used to give a fresh, new look to a home, office, vehicle, or other areas. The viscosity of the paint, which essentially serves as a measure of its thickness, is an important factor to consider.

Viscosity itself is concerned mostly with the paint’s “resistance” to disruption. In simple terms, it measures the paint’s thickness and determines whether the paint can be applied with a brush, a roller, a sprayer, or other methods of application. In most cases, interior paints for the home come in a nearly uniform level of viscosity that makes them perfect for brushes or rollers. Those homeowners or contractors using a sprayer, however, need to be more concerned with the exact viscosity of the paint to ensure that it can be applied uniformly to the surface without uneven ridges, tough application, or even damage done to the sprayer during painting.

Considering Viscosity: How to Relate Paint Thickness to Everyday Life

The various levels of paint viscosity can actually be compared to materials used in everyday life. Most people are familiar with the viscosity, or lack thereof, of a typical glass of water. If a glass of water gets spilled, it easily splashes everywhere and runs all over the table, the counter, and the floor. The very thin nature of water makes it hard to control the substance, though it does make water perfect for spraying finer mists, watering plants with a garden hose nozzle, and other key applications that rely on the relatively thin nature of water.

Maple syrup, conversely, does not simply run out of the container and all over the floor if it gets spilled. Sure, gravity will surely pull the syrup out of the container eventually, but this will take a great deal more time than it would with a glass of water. That’s because maple syrup is quite a bit more viscous than water, meaning its viscosity level is significantly higher. While water works well with garden hoses, water bottles, and sprinkler systems, maple syrup simply would not stand up to the task. It’s best used with a bottle that can force the syrup out, requiring more effort but also ensuring that syrup will stick more ably to the surface than would water in a similar situation.

Measuring the Viscosity of Paint: How is it Done?

Because most people are more familiar with selecting a paint color and referencing a complex series of samples and paint chips, they’re often not sure exactly how to measure viscosity or how the thickness of any paint can be altered after it has been mixed and brought home for everyday use. The good news, though, is that measuring the viscosity of paint is actually rather easy when using a device known as a viscosity cup. This “cup” of sorts looks like a combination between an actual cup and a measuring cup, featuring an area for scooping up paint and a handle for keeping the paint steady while viscosity is measured. At the bottom of this cup, a small hole is drilled that allows the paint to stream through, back into the bucket, until the cup is empty.

It is the amount of time between when the cup was filled with paint and when the last bit of paint exits through the hole in the bottom of the cup that is used to measure the level of viscosity in today’s paints. Each viscosity cup, like the famous Zahn cup, is paired with a set of instructions for measuring this period of time and then converting it in a measurement of the viscous nature of the paint. Those who are looking to either thicken or thin their paint can simply add solvents or thickeners to produce their desired result, using trial and error to find the level of paint viscosity that will work for automotive purposes, home paint sprayers, or even artistic applications where the running of paint would be rather detrimental to the person attempting to create a work of art.

Why Bother with Paint Viscosity Measurements in the First Place?

Among those who are not familiar with the viscosity levels of paint and how the measure of viscosity might affect performance, it can be a bit complicated to understand exactly why anyone would concern themselves with exactly how thick a can of paint actually use. After all, most people are used to simply dumping it out, rolling it on, and letting it dry. In the most basic of scenarios, this works well and it results in a quick interior design overhaul that can enliven a space in the home.

Other applications, though, require a great deal more precision when it comes to the actual thickness of the paint and its ability to either “run” and become very thin, or to resist running and use added thickness for a specific purpose. To better understand exactly why and when viscosity is so important to painters, designers, mechanics, and other professional creatives, it’s worth pointing out a few key scenarios where added thickness, or the lack thereof, makes a real impact.

The Artist: Dependent on Just the Right Level of Paint Thickness

When someone views an artistic painting that has made its way from the artist’s studio to the living rooms or hallways of their neighborhood, what they’re viewing is a complex balancing act between color, brush strokes, and the overall viscosity of the paint that was used to create the work of art in the first place. Artists, perhaps more than any other trade where paint is a key tool, depend on viscosity to ensure that their paint is able to create a cohesive picture, or visual effect, without running or pooling on the canvas. Artists tirelessly thicken their acrylic paints, to the point where they are sometimes added to the canvas not with brushes, but with metal scrapers and harsher edges that work with very thick paints.

The Mechanic: Automotive Paints Require Much Less Paint Viscocity

While thick paint is perfect for artistic applications, to the point that many of today’s oil-based paints come in tubes and more closely resemble paint, such paint compositions would be a detriment to vehicles. That’s because mechanics spray paint onto vehicles, preferring a very thin and very light coat to ensure even, uniform coverage. This thinner, lighter form of paint also helps to guard against surface abnormalities that might cause the paint to chip, crack, or peel very soon after application. Typically, mechanics and body shop professionals add a great deal of solvent or turpentine to their paint in order to thin it down and make it work properly with automotive paint spraying equipment. For comparison’s sake, the paint sold in home improvement stores for use throughout the home is often more than two times thicker than the paint needed for automotive work.

House Paint Viscocity: Even Traditional Paints Need a Little Work Sometimes

Paint is not applied in the same way by every homeowner. While the vast majority of people probably roll or brush paint onto their walls or exterior materials, a large and growing number of homeowners actually prefer paint sprayers to get the job done more quickly and in a more uniform manner. Paint sprayers, however, do not work with paint that has been mixed by retail stores. That paint is generally too thick, and it can result in either an uneven coating on the wall’s surface or “splotchy” painting that causes the sprayer to clog and malfunction. In these situations, homeowners will either need to purchase paint mixed to the right house paint viscocity level for their paint sprayer, or they’ll need to use a viscosity cup to measure the paint’s thickness and adjust it to the manufacturer’s suggested level so that their sprayer works perfectly both inside and outside the home.

Paint Viscocity: An Important Measure of Paint Capability and Durability

The viscosity of paint is a key indicator of the paint’s intended use, as well as its ability to deliver an even and uniform coating to the desired surface. In some applications, thicker paint is simply a better option. It’s thicker, resists running or dripping, and makes for great artistic work that can draw in an audience.

Thinner paints, though, are perfect for automotive and interior sprayers, while paint with just a slightly higher level of viscosity is perfect for rolling onto the wall and redecorating a room with ease. When the time comes to choose a paint color for automotive work, interior design alterations, or the modification of a home’s facade, remember to focus on viscosity as well as on the hue of the paint being chosen. With careful attention to this often forgotten detail, buyers can ensure that they’re picking the right paint for the job, able to withstand wear and tear, while working perfectly with any instruments being used to apply the paint.

  • Ruben André Bjørkevik

    I am terribly sorry… but this article is lika hearing a politician talk… a whole lot of words but little said…

  • Rich

    Nice article – too bad that “viscosity” is spelled wrong in several places. :)

    • Guest

      Yea, your smart.

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