Matting Agent for Polyurethane (PU) Coatings.

Wax-treated precipitated silica with D50 of 3–5 µm works best for 2K PU coatings. These grades minimize isocyanate consumption while delivering consistent gloss reduction. GMATT 200-H is a standard choice for solvent-borne 2K PU systems at 3–5% loading.

Matting silica reduces pot life by 10–20% at typical loading levels due to increased surface area and moisture pickup. At 6% loading, a 3-hour pot life drops to about 2.5 hours at 23 °C. Keep silica moisture below 4% and add only to the polyol side.

Haze results from coarse silica particles scattering light or poor wetting leaving micro-voids in the film. Controlling D95 below 12 µm and pre-dispersing at high shear in the polyol eliminates both causes. Avoid adding silica directly to the mixed 2K system.

No — solvent-borne PU uses hydrophobic-treated silica, while waterborne PU needs hydrophilic or lightly treated grades to prevent flotation defects. Using a hydrophobic grade in waterborne PU causes surface cratering and inconsistent gloss.

In solvent 2K PU, silane-treated silica (GMATT 200-S, D50 3.5 µm) reaches 10–20 GU at just 3–4% loading on a 40 µm film. Finer particle sizes are more efficient — coarser grades need higher loading and risk haze in clear systems.

Always add to the polyol (Part A) side. Adding silica to the isocyanate component triggers moisture-driven side reactions, generates CO₂ micro-bubbles, and drastically shortens pot life. Pre-disperse in polyol at high shear before mixing with hardener.

For clear 2K PU lacquers on wood and furniture, GMATT 200 Series with D50 3–5 µm delivers reliable low-gloss performance without haze — pre-disperse in the polyol component and keep silica moisture below 4% to protect pot life.

SEMITECH matrix · co-purchase