Advancing Extender Technology for Durable, Low-Sheen Architectural Coatings

By Daniel Fonseca, Lead TS&D Specialist, The Dow Chemical Company

The demand for durable, low-sheen architectural coatings continues to grow. Matte and low-gloss finishes are increasingly favored for their modern aesthetics and ability to mask surface imperfections. To achieve matte finishes, formulators have traditionally relied on inorganic extenders such as mineral fillers, silica, and ceramic microspheres. However, improving surface durability, especially scuff and mar resistance, often requires higher-sheen coatings, which are prone to demonstrate application defects across large surfaces and are less effective at hiding wall defects. Additionally, these extenders are typically supplied as powders, adding processing steps and complexity during paint manufacturing.

Dow’s new class of organic extender technology helps to address these limitations. OPTI-MATT™ MT-8 Extender is a 100% acrylic emulsion designed to replace or supplement inorganic extenders, deliver enhanced durability, improve color transfer resistance, and offer reduced manufacturing complexity through grind-free formulating.

Enabling Durable Interior Matte Finishes

In Interior wall paint applications, OPTI-MATT™ MT-8 Extender helps to enable low-sheen finishes while offering outstanding resistance against scuffing and marking, and minimizing color transfer, particularly in deeply colored paints, as shown in Figure 1 and 2. OPTI-MATT™ MT-8 Extender is paired with a resin or blend of resins to optimize the final performance profile of the paint. The exact balance of resin, OPTI-MATT™ MT-8 Extender and other ingredients in the formulation are all critical levers for achieving a specific target gloss and desired performance characteristics. Coatings made with OPTI-MATT™ MT-8 Extender preserve surface appearance better, resulting in finishes that last longer and keep their original look, which lowers the need for maintenance or repainting.

Expanding Performance Across Specialty Applications

Beyond interior wall paints, OPTI-MATT™ MT-8 Extender has shown broad relevance across specialty coatings, where the balance between appearance and durability is often even more critical because of greater exposure to abrasion, environmental stress, and repeated contact. Across these applications, it consistently improves scuff and mar resistance, color transfer resistance, and hot tire pickup resistance in concrete coating systems, while maintaining properties such as adhesion, chemical resistance, and overall performance, as illustrated in Table 1. This balanced performance profile helps formulators target higher-performing coatings without the trade-offs commonly associated with traditional inorganic extenders.

A key advantage of OPTI-MATT™ MT-8 Extender in specialty coatings is its formulation flexibility. It can fully replace inorganic extenders or be used as a partial replacement to optimize the cost and performance balance. Results show that replacing inorganic extenders with 50–60% of OPTI-MATT™ MT-8 Extender can retain much of its performance benefit which gives formulators greater freedom in extender selection while maintaining target PVC, gloss, and film properties.

As shown in Figures 3 and 4, OPTI-MATT™ MT-8 Extender delivers excellent scuff and color transfer resistance in specialty coatings, similar to its performance in interior coatings. Scuff resistance was evaluated based on visual appearance and ΔE76 between rubbed and unrubbed areas, where a lower value indicates better scuff resistance. Color transfer resistance was visually rated on a 0–5 scale, where 5 indicates no color transfer. Compared with both the traditional extender (nepheline syenite) and the competitive matting agent (ceramic microspheres), paints containing OPTI-MATT™ MT-8 Extender demonstrated improved scuff and color transfer resistance across multiple specialty applications.

A ~50/50 blend of OPTI-MATT™ MT-8 Extender and a traditional extender (nepheline syenite) was also evaluated. The results showed that a blend of extenders still provides significant improvement in scuff resistance. Even partial replacement with OPTI-MATT™ MT-8 Extender improved both scuff and color transfer resistance compared with the traditional extender alone.

Garage floor coatings represent one of the most demanding applications for one-component, waterborne systems because they are exposed to repeated mechanical stress, heavy foot and vehicle traffic, and the intense localized pressure generated by hot tires. To perform well in this environment, coatings must resist both visible surface marking and damage caused by coating pickup under heat and load. As shown in Figure 5, OPTI-MATT™ MT-8 Extender improved hot tire pickup resistance compared with both the traditional extender (nepheline syenite) and the competitive matting agent (ceramic microspheres), as evidenced by reduced tire marking on the concrete surface and less coating transfer to the tire. Notably, this benefit was also maintained in a ~50/50 blend of OPTI-MATT™ MT-8 Extender and a traditional extender (nepheline syenite), indicating that full replacement is not required to achieve meaningful performance gains in demanding garage floor applications.

As shown in Figure 6, formulations containing OPTI-MATT™ MT-8 Extender exhibited less breakthrough than those formulated with the traditional extender (nepheline syenite) after 1000 Taber abrasion cycles, indicating improved resistance to wear under demanding conditions. This result suggests that OPTI-MATT™ MT-8 Extender helps maintain coating integrity for longer periods of mechanical stress. A similar improvement in abrasion resistance was also observed in a sport surface formulation, demonstrating that this benefit extends across multiple specialty coating applications.

As shown in Figures 7 and 8, coatings formulated with OPTI-MATT™ MT-8 Extender also demonstrated improved adhesion to concrete and better alkali resistance than formulations containing the traditional extender (nepheline syenite). These properties are especially important in specialty coatings used on surfaces exposed to heavy foot traffic, moisture, and alkaline substrates, where long-term durability and coating integrity are critical. The results indicate that OPTI-MATT™ MT-8 Extender can enhance not only surface durability, but also key protective properties needed for demanding environments.

Clear concrete sealers are designed to protect substrates while maintaining the natural look of the surface, making them especially valuable in applications where appearance is just as important as durability. In these systems, achieving the right balance between gloss reduction and surface performance can be challenging, since excessive matting can sometimes compromise clarity or protective properties. As shown in Figure 9, OPTI-MATT™ MT-8 Extender delivers effective matting at equal PVC compared with a competitive matting agent (ceramic microspheres). This allows formulators to achieve low-gloss finishes while preserving the visual character of the concrete. This performance makes it a useful tool for developing sealers that combine aesthetic appeal with the durability required for concrete protection.

Delivering Long-Term Performance in Weathered Exterior Coatings

Exterior coatings are designed to protect and beautify surfaces exposed to UV light, moisture, and temperature fluctuations. They must deliver durability, adhesion, and resistance to cracking, fading, and weathering to extend service life while preserving appearance. As shown in Figures 10 and 11, OPTI-MATT™ MT-8 improves performance in exterior deep-base wall coatings, providing better crack resistance, color development, and tint retention than the traditional extender (nepheline syenite) and commercial control paint across a broad range of colorants. These results indicate that OPTI-MATT™ MT-8 Extender can help formulators achieve durable, low-sheen exterior coatings that maintain both protective performance and visual appeal over extended outdoor exposure.

Conclusion

OPTI-MATT™ MT-8 Extender represents an innovative approach to matting in architectural coatings. By replacing traditional inorganic extenders, it enables matte through eggshell finishes with improved scuff and mar resistance, reduced color transfer, and strong performance across a broad range of interior, exterior, and specialty applications. In garage floor coatings, solid color wood stains, porch and patio coatings, sports surfaces, and clear concrete sealers, OPTI-MATT™ MT-8 Extender delivered enhanced durability while maintaining key baseline properties such as adhesion, chemical resistance, and overall film performance. In exterior coatings, OPTI-MATT™ MT-8 Extender space provides improved cracking resistance and color retention in deep base formulations. In addition to these performance benefits, it has compatibility with multiple resin systems to support greater formulation flexibility and simplified manufacturing through grind-free or post grind addition. It also enables optimal cost performance balance through partial replacement of inorganic extenders. Together, these attributes position OPTI-MATT™ MT-8 Extender as a versatile technology for formulators seeking to achieve durable, low-sheen coatings without the trade-offs traditionally associated with traditional extenders.