Introducing Powder Coating Perspectives, a new column brought to you by experts from The ChemQuest Group. This series will delve into the latest advancements, challenges and practical insights shaping the powder coatings industry — from formulation strategies to real-world applications.

The coatings industry relies on a variety of standardized test methods to evaluate coatings for an assortment of properties and purposes. The two most widely recognized standards organizations are ASTM (American Society for Testing and Materials) and ISO (International Organization for Standardization). While these standards cover a broad range of coating properties, other organizations, such as the Canadian Standards Association (CSA), provide standards for specialized applications like pipeline coatings.

Standardized test methods offer clear benefits by:

• Eliminating the need to constantly create new methods for common performance parameters.
• Saving time by providing accepted procedures that don’t need to be re-justified for each project.
• Allowing for data comparisons across laboratories.

These benefits come with an important limitation, however, in that standardized tests often fail to replicate the actual conditions that coatings experience in the field. In other words, while standardized methods are valuable for product development, benchmarking raw materials and general performance comparisons, they can fall short when troubleshooting specific field issues or fine-tuning formulations for real-world applications. Let’s look at an example to illustrate this limitation.

A Case Study: Improving Mar Resistance for Powder-Coated Parts

Recently, a company that manufactures and applies powder coatings to metal parts sought help addressing an issue encountered during packaging and installation. Described as “marring,” the problem occurred when coated parts rubbed against each other, resulting in visible marks and changes in texture or gloss.

Although the manufacturer had the ability to reduce the issue during the packaging process, it could not eliminate the problem occurring during installation by field contractors. Thus, the company approached ChemQuest Powder Coating Research to request a reformulation of the powder coating to enhance its mar resistance.

To address this issue, the fundamental question became: Which test method should be used to evaluate improvements in mar resistance? Although there are standardized tests like Mar Resistance (ASTM D5178) and Taber Abrasion (ASTM D4060), our team recognized that these tests might not accurately replicate the client’s field conditions. Hence, the decision was made to develop a custom test method that would better mimic the real-world scenario.

Developing a Real-World Test Method

When creating a test method tailored to specific field conditions, several key principles should be followed:

• Relevance to real-world issues: The test must closely mirror the actual conditions causing the failure in the field, rather than serving as a mere indicator of general performance.
• Reproducibility: The method should minimize variables to ensure consistent and repeatable results.
• Sensitivity to variations: The test must be able to distinguish between different formulations or process changes to ensure that improvements can be accurately assessed.

In this case, the goal was to replicate two coated metal parts rubbing against each other, leading to a change in appearance (both gloss and texture). A straightforward test method was devised: two coated metal parts were prepared, and one was slid across the other to induce marring. However, it was critical to control variables such as the force applied during sliding, as inconsistencies could introduce errors and affect the reproducibility of the test.

A practical solution was to use a fixed weight on the sliding part, ensuring a consistent downward force across all tests. This setup allowed our team to push the weighted part horizontally over the test panel, simulating the real-life contact conditions that caused the marring.

Quantifying the Results

The final step in developing the test method was determining how to measure the effect. In this instance, a visual assessment for texture and change in gloss was sufficient to evaluate improvements. By comparing gloss measurements before and after the test, the team could quantify the level of marring and assess the effectiveness of different formulations.

It’s important to remember that the purpose of this test was not for academic precision but to identify whether meaningful improvements were achieved in a specific application. Overcomplicating the method could obscure practical results, so keeping the approach straightforward was key.

Achieving Meaningful Results

While standardized tests are invaluable tools in the coatings industry, they have limitations when it comes to solving specific, real-world problems. Too often, formulators rely on a standardized test only to find out later that the issue in the field was not improved by their coating modifications. Custom test methods, tailored to replicate the actual conditions a coating will experience, can provide more accurate insights and drive meaningful product improvements.

For applicators and end users who experience coating issues in the field, working with a coating supplier or a third party that takes the time to understand their specific situation can lead to more reliable and robust coatings that perform as expected in their unique environments. When evaluating or troubleshooting coating performance, remember that sometimes the most effective solutions come from simple, well-thought-out tests that directly address the issue at hand.

To learn more, contact the author at ecasebolt@chemquest.com or visit https://chemquest.com/cqpcr.