How to Formulate Waterborne Additives for Architectural Coatings? Technical Challenges and Solutions
1. Waterborne is a major trend, but challenges follow
Environmental regulations continue to tighten VOC limits, and architectural coatings have largely completed the transition to waterborne systems—interior emulsion paints, exterior coatings, real-stone/texture coatings, and waterproof coatings all use water as the continuous phase. However, “waterborne” does not mean “simpler.” Formulation engineers must simultaneously address:
- Scrub resistance and weatherability: Exterior coatings must withstand rain, UV radiation, and temperature fluctuations, while interior coatings must resist repeated scrubbing. The film strength of emulsion paints depends directly on the dispersion state of film-forming materials and pigments/fillers;
- Storage stability: Waterborne systems are susceptible to pH, temperature, and microbial effects. Pigment/filler settling, separation, and mildew are common issues;
- Application performance: Roller application, spray application, and trowel application impose different requirements on foaming, leveling, and open time. Foam and shrinkage craters are directly visible in wall appearance.
Water has high surface tension (approximately 72 mN/m), and emulsions and surfactants tend to stabilize foam. This makes “additive combination” an unavoidable task in waterborne formulation.
In short: Waterborne technology solves the environmental challenge but passes three major contradictions—scrub resistance, storage stability, and application performance—to the additive system. Only with the four major additives each performing their own role can a balance be achieved.
2. Roles of the four major additives: wetting, dispersing, defoaming, and leveling
| Additive | Problem addressed | Consequences of failure/overdose |
|---|---|---|
| Wetting agent | Lowers surface tension, wets pigments/fillers and substrate, improves grinding efficiency | Poor dispersion, shrinkage craters, poor adhesion |
| Dispersing agent | Adsorbs on pigment/filler surfaces, breaks agglomerates, prevents settling and re-flocculation | Flooding/floating, color deviation, viscosity rebound, reduced hiding power |
| Defoamer | Destroys/inhibits foam, ensures no foaming during grinding, paint mixing, and application | Pinholes, fisheyes, film defects, reduced scrub resistance |
| Leveling agent | Balances film surface tension, eliminates brush marks and orange peel, improves appearance | Visible brush marks, orange peel, uneven gloss |
The combination logic of the four: the wetting agent ensures “spreadability,” the dispersing agent ensures “stability,” the defoamer ensures “no air entrainment,” and the leveling agent ensures “good appearance.” A missing or overdosed component will expose problems elsewhere—for example, a formulation with insufficient wetting cannot be saved by adding a leveling agent when shrinkage craters occur.
In short: The four major additives form a relay chain of “spread—stabilize—de-air—finish.” A missing or overdosed link will show up in the final product.
3. Additive combination schemes by scenario
3.1 Interior emulsion paint
Key priorities: hiding power, scrub resistance, application feel, and storage stability.
- Wetting: Toynol® FS-204 (acetylenic diol nonionic wetting agent with foam control; active matter ≥98%; static surface tension 32.8 / dynamic 33.3 dyn/cm at 0.1% aqueous solution)—fast dynamic wetting and low-foam performance, suitable for high-speed dispersion and roller application systems;
- Dispersing: DS series waterborne dispersants (e.g., DS-172 for general-purpose pigment dispersion, subject to TDS), with gradient small-scale trials in titanium dioxide and other inorganic pigment systems;
- Defoaming: Polyether-type Foamic-028 in the letdown stage (sustained foam inhibition, good compatibility); acetylenic diol DF-57/DF-80D for foam suppression in the grinding stage;
- Leveling: SI-800 or wetting/leveling agents ET-204/205/206 (balancing film surface tension, reducing brush marks).
3.2 Exterior coatings
Key priorities: weatherability, water resistance, dirt pickup resistance, and a wide application window.
- Wetting/dispersing follow the same route as above; exterior coatings place higher demands on storage stability, and dispersant dosage and system compatibility must be verified by heat-aging storage testing;
- Defoamers should prioritize sustained-performance types (polyether-based Foamic-028) to avoid excessive silicone defoamer affecting recoating and intercoat adhesion;
- Elastomeric exterior and textured systems have high viscosity; deaeration requirements should be assessed (Foamic series matched per TDS).
3.3 Real-stone coating / texture coating
Key priorities: high pigment/filler loading, anti-settling, and no foaming during spray application.
- High-solids systems demand fast wetting; the Superwet series (low-foam performance with penetrating and spreading action) suits thick-film spray application;
- Dispersing agents combined with suspension stabilizers (AN series) prevent settling and separation of colored sand;
- Defoamers should be validated under the actual spray process to avoid pinholes in thick films.
| Scenario | Wetting | Dispersing | Defoaming | Leveling |
|---|---|---|---|---|
| Interior emulsion paint | FS-204/Superwet | DS series | DF-57/DF-80D + Foamic-028 | SI-800, ET-204/205/206 |
| Exterior coating | FS-204/Superwet | DS series | Foamic-028 as primary | SI-800 direction |
| Real-stone/texture coating | Superwet series | DS series + AN suspension stabilizers | Validate by spray process | Depending on appearance requirements |
Validation path: Start with small samples—first fix the wetting and dispersing agents, and measure grinding fineness and viscosity; add defoamer in the letdown stage and check drawdown/spray appearance (pinholes, fisheyes, shrinkage craters); then add leveling agent to evaluate brush marks and orange peel; finally, conduct 50°C heat-aging storage for one week plus application simulation, changing one variable at a time in each step.
In short: Interior coatings focus on “hand feel and hiding,” exterior coatings on “weatherability and stability,” and real-stone coatings on “anti-settling and foam control.” The additive priorities differ by scenario, but the validation path is always “single-variable gradient small-scale trials.”
4. Common pitfalls and precautions
- Wetting agent overdose stabilizes foam: Excessive conventional surfactants can significantly stabilize foam and increase defoaming burden—low-foam wetting agents (FS-204/Superwet direction) reduce foam at the source;
- Dispersing agent overdose causes thickening: After adsorption saturation, free dispersant triggers flocculation and thickening, reducing hiding power—dose by gradient per TDS;
- Silicone defoamers leave no way back: Exterior coatings require recoating and intercoat adhesion; excessive silicone can cause shrinkage craters and impair adhesion—prioritize polyether/acetylenic diol routes;
- Testing only fresh paint without storage testing: Mildew, settling, and separation often emerge during storage—heat-aging and mildew resistance evaluation are mandatory;
- Ignoring differences in application methods: Roller, spray, and trowel application have different foaming and leveling requirements—additive combinations must be validated under the actual application method.
FAQ
Q1: What should be done when scrub resistance decreases after switching to waterborne architectural coatings?
A: Scrub resistance is related to the film-forming material and the dispersion state of pigments/fillers. First check whether the dispersing agent has fully dispersed the titanium dioxide/fillers (hiding power, fineness), then verify whether defoaming is complete (residual microfoam reduces film density). Troubleshoot using single-variable gradient testing.
Q2: How to solve brush marks and orange peel in roller-applied emulsion paint?
A: Brush marks/orange peel result from insufficient leveling plus imbalanced surface tension. First confirm whether wetting and spreading are adequate (FS-204/Superwet direction), then add leveling agent (SI-800, ET series) to balance film surface tension, increasing dosage stepwise and observing drawdown results.
Q3: How to deal with foaming and pinholes in spray-applied real-stone coating?
A: High-solids thick-film systems impose high deaeration demands: check the defoamer type and dosage (validated under the spray process), and simultaneously assess whether the suspension stabilization system introduces excessive air bubbles (AN series matched per TDS). Conduct spray trials on actual samples for observation.
Q4: How to solve settling and separation in exterior coatings after storage?
A: First check whether the dispersing agent provides adequate stabilization of pigments/fillers (DS series by TDS gradient), then add suspension stabilizers/rheology modifiers (AN series direction) to enhance settling resistance. Conduct 50°C heat-aging storage for one week with single-variable troubleshooting.
Q5: What additive combination is recommended for waterborne architectural coatings?
A: A standard starting point is “wetting agent (FS-204/Superwet) + dispersing agent (DS series) + defoamer (DF/Foamic series) + leveling agent (SI-800/ET series),” adjusted by scenario for interior/exterior/real-stone coatings. Specific product grades and dosages are subject to TDS and sample validation.
Key conclusions
- Waterborne technology solves the environmental challenge, but the three major contradictions—scrub resistance, storage stability, and application performance—must be balanced through the additive system
- Roles of the four major additives: wetting for “spreadability,” dispersing for “stability,” defoaming for “no air entrainment,” and leveling for “good appearance”—none can be omitted
- Scenario-based schemes: interior emulsion paint (FS-204 + DS series + DF/Foamic + SI-800/ET), exterior coatings (sustained foam control prioritized), real-stone coatings (Superwet + AN suspension stabilization + spray validation)
- Validation path: wetting/dispersing → fineness/viscosity → defoaming/appearance → leveling/appearance → heat-aging storage and application simulation, with single-variable changes at each step
- Common pitfalls: wetting agent overdose stabilizing foam, dispersing agent overdose causing thickening, silicone defoamers affecting recoating, and neglecting storage testing—data subject to TDS
