Hydrophilic Surface Modification: The Seeding Solution
The most common failure mode of silica matting agents in waterborne coatings is seeding — the formation of visible agglomerates (typically 0.5–2 mm) caused by hydrophobic silica surfaces bridging across the aqueous phase during storage or dilution. GMATT WB is engineered with a hydrophilic surface modification that makes the silica genuinely water-compatible: each particle is surrounded by a stable aqueous solvation shell that prevents inter-particle bridging. The result is seeding-free performance through 12-month warehouse storage at 5–40°C and through the full dilution range encountered in architectural tinting base programs and on-site water addition.
Viscosity Stability Through Water Dilution
Architectural and industrial waterborne coatings are frequently diluted with water at point of use. When a silica grade with hydrophobic or incompatible surface chemistry is used, water addition can trigger silica flocculation — causing a non-linear viscosity spike that makes the diluted paint difficult to apply and results in gloss variation on the wall or substrate. GMATT WB maintains stable, individual particle dispersion throughout water dilution. Viscosity decreases predictably and linearly with water addition, ensuring consistent rollability and spray atomisation for contractors and production lines alike.
Compatibility with Waterborne 2K PU Systems
Waterborne 2K PU coatings use water-dispersed polyisocyanate (HDI or IPDI trimer) hardeners that are sensitive to reactive surface silanols on conventional silica grades. The surface silanols can react with isocyanate groups, consuming hardener and disrupting the stoichiometry — reducing crosslink density, film hardness, and chemical resistance. GMATT WB's hydrophilic surface modification caps the reactive silanol groups, preventing isocyanate consumption and ensuring the full polyurethane crosslink network develops. In waterborne 2K PU topcoat at 20–35 µm DFT, GMATT WB at 3.0–5.0 wt% delivers 60° gloss targets of 10–30 GU with full hardness and chemical resistance development.
Zero-VOC and Regulatory-Ready for Global Compliance
Waterborne coatings are the regulatory direction of the global coatings industry, driven by EU DNEL/DMEL frameworks, US EPA Architectural Coatings Rule, and China GB 18582-2020. GMATT WB contributes zero VOC, zero SVOC, and zero restricted heavy metals, aligning perfectly with the zero-VOC positioning of waterborne architecture and industrial coatings. SEMITECH provides a Declaration of Conformity and REACH compliance documentation to support customer qualification documentation for EU Ecolabel, China GB/T 9756-2018, and US EPA submissions.
When to Use GMATT WB for Waterborne Coatings
GMATT WB is the correct silica matting agent for any waterborne system where seeding defect risk, viscosity stability through dilution, or isocyanate compatibility (waterborne 2K PU) are formulation constraints.
| Scenario | Recommended Grade | Target DFT | Loading |
|---|---|---|---|
| Architectural emulsion, zero-VOC | GMATT WB | 20–35 µm | 2.0–4.0 wt% |
| Waterborne 2K PU topcoat | GMATT WB | 20–35 µm | 3.0–5.0 wt% |
| Waterborne wood clear coat, clarity | GMATT WB | 15–25 µm | 2.5–4.0 wt% |
| Industrial waterborne topcoat | GMATT WB | 25–45 µm | 3.0–5.0 wt% |
| Tinting base with water dilution | GMATT WB | 20–35 µm | 2.0–3.5 wt% |
Technical FAQ
GMATT WB formulation questions covering architectural emulsion, waterborne 2K PU, and zero-VOC industrial waterborne systems.
+What is the seeding defect in waterborne coatings and how does GMATT WB eliminate it?
Seeding is the formation of visible silica agglomerates (typically 0.5–2 mm diameter) in waterborne coatings during storage or dilution. It occurs when the silica surface has hydrophobic character (from wax or organofunctional treatment) that causes inter-particle bridging in the aqueous phase. GMATT WB carries a hydrophilic surface modification that makes the silica wettable by water, forming a stable solvation shell around each particle. This prevents inter-particle bridging and maintains individual particle dispersion through the full storage life and through point-of-use dilution.
+How does GMATT WB maintain stable viscosity through water dilution in architectural tinting systems?
In architectural tinting systems, the base paint is diluted with water at point of sale or on-site (typically 5–15% water addition). Silica grades with hydrophobic surfaces can flocculate during dilution, causing a viscosity spike that makes the diluted paint difficult to apply. GMATT WB's hydrophilic surface remains fully dispersed through the dilution range — viscosity decreases predictably with water addition rather than exhibiting the non-linear spike. This ensures consistent application properties for architectural coatings sold through tinting base programmes.
+What loading is recommended for GMATT WB in zero-VOC waterborne 2K PU topcoat?
In waterborne 2K PU topcoat (isocyanate-crosslinked, VOC < 50 g/L) at 20–35 µm DFT, GMATT WB at 3.0–5.0 wt% achieves 60° gloss targets of 10–30 GU with good chemical resistance and hardness development. The hydrophilic surface of GMATT WB is compatible with the water-dispersed polyisocyanate hardener used in waterborne 2K PU systems — preventing the silica-to-isocyanate reaction that standard gel silica surface silanols can trigger, consuming isocyanate and disrupting the stoichiometry.
+Is GMATT WB suitable for waterborne wood coatings where clarity is critical?
Yes. GMATT WB is available in a fine-particle sub-grade suitable for waterborne wood clear coats at 15–25 µm DFT, where transparency to the wood grain must be maintained. The hydrophilic surface ensures complete dispersion without agglomeration that would cause cloudiness in the clear coat. At 2.5–4.0 wt% loading, GMATT WB achieves 60° gloss of 15–30 GU in waterborne PU wood lacquer without haze in the cured film.
+Can GMATT WB be used in waterborne architectural coatings compliant with EU Ecolabel or GB/T 9756 standards?
Yes. GMATT WB is an inorganic synthetic amorphous silica classified as non-hazardous under CLP/GHS. It contributes zero VOC, zero SVOC, and zero restricted substances to the coating formulation. It is compatible with coatings formulated to comply with EU Ecolabel for indoor paints (VOC < 30 g/L for tinted, < 1 g/L for white), China GB/T 9756-2018 (interior wall emulsion paint), and US EPA Architectural Coatings Rule. SEMITECH provides a Declaration of Conformity on request.
Recommended Solution
For zero-VOC waterborne architectural, industrial, and 2K PU coatings where seeding defect and viscosity stability through dilution are non-negotiable, specify GMATT WB Series — hydrophilic-surface silica engineered for the aqueous waterborne environment.
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