Key Takeaways

• Dirt pickup resistance (DPUR) refers to a coating’s ability to avoid accumulating dirt.
• Self‑cleaning paints and coatings go further by incorporating mechanisms that release adhered dirt. 
• One of the earliest approaches to reducing dirt pickup involved benzophenone and other photoreactive species, technology used for many years in exterior coatings and resins. 
• There are many viable design strategies for exterior paints and coatings, and suppliers continue to innovate in this space. 
• Expect growing adoption of self‑cleaning technologies as demand for reflective (cool roof) coatings rises and sustainability efforts emphasize long‑lasting exterior performance.

Ideally, painted surfaces will stay looking like new as they age.  Painted exterior surfaces must do more than survive the weather; they must also continue to look clean and fresh over time. Polaris Chemical Consulting reviewed the topic of self‑cleaning coatings in its October 2024 newsletter.(1) This updated edition revisits that foundation and adds new insights, reflecting the continued interest in this area.

Self‑cleaning paints and coatings are formulated to shed dirt through built‑in mechanisms, allowing surfaces to remain clean without manual washing. They are related to (but distinct from) traditional dirt‑resistant coatings, which aim primarily to prevent dirt from adhering in the first place. Dirt‑resistant technologies have been explored since at least the 1960s.

Exterior architectural coatings must remain flexible to accommodate dimensional changes in substrates such as wood. However, softer coatings tend to attract and retain dirt. A 1967 DuPont patent addressed this challenge by combining soft latex copolymers with photoreactive benzophenone. UV exposure triggers surface crosslinking, creating a harder, dirt‑resistant outer layer while leaving the underlying film flexible for crack resistance and adhesion.(2) This “layered” effect has been used for many years and remains foundational in many resin and paint offerings.

Today, numerous commercial products claim dirt pickup resistance.(3,4,5) Cool roof coatings, in particular, depend on this property because accumulated dirt reduces solar reflectivity and undermines energy‑saving performance.

Beyond Dirt Pickup Resistance: Mechanisms for Self-Cleaning

Dirt pickup resistance alone does not guarantee dirt removal. Self‑cleaning coatings incorporate mechanisms that actively release adhered dirt. Examples include:

• “Rain‑activated cleaning,”  where surface chemistry promotes dirt removal during precipitation.  There are architectural coating products on the market that utilize this approach.(6,7)
• “Photocatalytic titanium dioxide,” which can be used in inorganic coatings.(8)  Under sunlight, TiO₂ generates hydroxyl radicals that degrade organic contaminants at the surface.

Understanding Dirt Pickup: What the Research Shows

A comprehensive study examined how laboratory tests correlate with real‑world dirt pickup performance of architectural coatings.(9) Dirt pickup occurs in three stages:

1. Deposition of dirt onto the surface 

2. Adhesion and entrenchment of dirt 

3. Shedding and release of dirt 

Panels were exposed outdoors in Guangzhou, China, and Chennai, India—two environments that produced clear differentiation among coatings marketed as dirt‑resistant. Key findings include:

• Deposition tests (e.g., aerosolized carbon black) showed little differentiation and did not predict real‑world performance. 
• Water‑induced surface creep tests, both immersion and slurry‑based—also failed to correlate with outdoor results. 
• Thermal creep testing (dusting panels, then aging at 45 °C for three days) correlated strongly with field exposure. 
• Dirt release improved with higher PVC and more hydrophilic surfaces.

Implications for Coating Design

The study and a related reference(10) suggest several design principles:

• Thermal surface creep is a major driver of DPUR; harder surfaces reduce dirt entrenchment. 
• High PVC and hydrophilicity promote dirt shedding and self‑cleaning.
• Binder selection is critical: crosslinking systems, benzophenone‑modified latexes, and core‑shell polymers can enhance performance. 
• Higher‑Tg binders improve hardness but must be balanced with flexibility requirements. 
• Surface porosity should be minimized to avoid capillary dirt entrapment. 
• Increased surface slip reduces particle adhesion.

Recent Developments

Self‑cleaning technology remains an active area of research. At the Western Coatings Show in October, several papers focused on dirt pickup resistance:

• Ziniu Yu presented work on colloidal silica to improve DPUR in waterborne paints.(11)  Nouryon also offers  colloidal silica for improvement of dirt pickup resistance in architectural coatings.  
• Another paper examined PFAS‑free additives designed to deliver high dirt pickup resistance without fluorochemicals.(12)

Looking Ahead

Self‑cleaning and dirt‑resistant architectural coatings offer clear advantages: better long‑term appearance, reduced maintenance, and improved sustainability. Many technologies—both legacy and modern—are available today, with newer approaches such as core‑shell latexes gaining traction. As reflective coatings grow in importance and sustainability expectations rise, self‑cleaning technologies will play an increasingly central role in exterior architectural coating design.

(1) July-Dec 2024 Newsletters 

(2) Trevor B. Hill, “Latex Paint Containing Benzophenone,” U.S. Patent 3,320,198, May 16, 1967.

(3) SuperPaint® Exterior Acrylic Latex Paint - Sherwin-Williams 

(4) Exterior Paint and Primer All-in-One | BEHR ULTRA® Exterior Paint | Behr 

(5) Residential Roof Coatings | Rust-Oleum (rustoleum.com)

(6) Emerald Rain Refresh Exterior Acrylic Latex Paint | SherwinWilliams 

(7) LOXON Self-Cleaning Acrylic Coating | SherwinWilliams

(8) EXOCOAT 151B | Self-Cleaning Nano Titanium Oxide Coating 

(9) Scott Brown, Michael Diebold, Daniel Kraiter, Carlos Velez, and Peter Jernakoff, “Towards a Comprehensive Understanding of Dirt Pickup Resistance,”  Coatings Tech, p. 14, June 2020.

(10) Dirt Pickup Resistance (DPUR) - Phases, Formulation & Test Methods

(11)  Ziniu Yu, “Colloidal Silica in Water-Based Architectural Paints: Enhancing Dirt Pickup Resistance and Performance,” Western Coatings Society Show, Las Vega, NV, October 19-22, 2025.

(12) Emma Blezinski, “PFAS-Free Additives for Superior Dirt Pickup Resistance,” Western Coatings Society Show, Las Vega, NV, October 19-22, 2025.

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(photo credit: picture generated by Microsoft Copilot)