Part 5 of 6: How “Just a Little Thinner” Impacts VOC Emissions in Industrial Coatings

Chef makes a meal without a recipe

6-Part Blog Series: The Role of High-Performance Coatings in Shrinking the Carbon Footprint

In part four of this blog post series, we discussed the key data points that should be used when selecting an industrial coating system in order to accurately forecast volatile organic compound (VOC) emissions.

In this next blog post, we will examine how the human factor—such as common practices across the industrial coatings industry—can impact actual VOC emissions.

One common industry practice occurs when painters are preparing to apply industrial coatings for the first time. With catalyzed coatings, part A and part B are mixed together according to the instructions. Purely out of habit, a stir stick is then used to assess the consistency of the coating and to add thinner to the mixture until it “feels right.”

To be clear, many of these craftsmen who add thinner to feel can effectively “lay it down as smooth as glass”—producing some of the most beautiful, seamless finishes. This is similar to a seasoned chef who does not measure, but instead adds ingredients and spices “to taste.” Although this method works in some cases, it’s not ideal if you are not a trained chef or have specific dietary restrictions. In the industrial coatings industry, if low VOC emissions are required, the painter needs to carefully measure the thinner and find alternatives wherever possible.

Let’s take a look at the effect on total VOC emissions if “just a little extra” thinner is added to an industrial coating. Assume, for example, that an annual maintenance program will use 1,000 gallons of epoxy paint. For this illustration, let’s say the epoxy used is 75% solids by volume, and the 25% volatiles are VOCs with a weight of 1.8 lbs per gallon. At 1,800 lbs of VOC emissions, this would be considered a high-solids, low-VOC epoxy that falls well within the acceptable VOC limits in most legislative regions.

1,000 gal of paint x 1.8 lbs VOCs per gal = 1,800 lbs VOC emissions

That 1,000 gallons of epoxy can protect upwards to 200,000 ft² of steel surface. In the big picture of sustainability, the ability to protect large areas of steel from corrosion is a very good thing. That said, it’s important to still be mindful of the VOC emissions—especially those that are unnecessary.

Let’s next consider the effect of adding 10% extra thinner to the coating, whether or not it is actually needed. For this illustration, we’ll assume the thinner contains 7 lbs of VOCs per gallon. In addition to the 1,000 gallons of epoxy, an additional 10%—or 100 gallons—of thinner is added to the 1,000 gallons of paint prior to application.

100 gals of thinner x 7lbs VOCs per gal = 700 lbs VOC emissions

As you can see, the VOC emissions “cost” for protecting 200,000 ft² of steel from corrosion rose from 1,800 lbs VOCs to 2,500 lbs—a nearly 40% increase!

Suitable thinners for industrial coatings are absolutely necessary. They are required to clean equipment and, at times, to improve the application characteristics of a coating when environmental conditions are not ideal. For instance, hot and windy conditions, or even cold weather, may require special thinners to achieve a successful application.

Although thinners are often a necessary part of the application process, spray equipment can be adjusted to handle higher-viscosity coatings instead of using thinners with VOCs to lower the viscosity of the coatings. This small adjustment can have a big impact on reducing VOC emissions.

In the final part of this blog post series, we will explore the various strategies that can be used to reduce VOC emissions by painting less.

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