Physical & Surface Specifications
Both GMATT 200 series and AEROSIL OK 520 are organically treated precipitated and fumed silica matting agents designed to reduce gloss in solvent-based coatings. AEROSIL OK 520 is a hydrophobic fumed silica with a BET surface area of ~170 m²/g, treated with HMDS (hexamethyldisilazane). GMATT 200 series offers a comparable BET range of 130–160 m²/g with proprietary surface treatment that delivers equivalent hydrophobicity. Median particle size (D50) for both falls in the 3–5 µm range after dispersion, though GMATT achieves tighter distribution control at the 4 µm target — critical for consistent film appearance in architectural and industrial topcoats.
Gloss Reduction & Film Performance
At 3–5% loading in a typical alkyd or polyurethane system, both products reduce 60° gloss to 10–20 GU. GMATT 200 reaches sub-10 GU gloss at 5% loading in solvent-borne polyurethane, matching AEROSIL OK 520 performance at equivalent dosage. Film clarity remains comparable — neither product introduces measurable haze below 6% loading. Where GMATT shows a practical edge is viscosity impact: its optimized particle morphology produces 10–15% lower Hegman grind values at equal loading, meaning faster dispersion and less thickening in high-solids formulations. Both maintain thermal stability up to 300 °C, suitable for coil coating and industrial bake cycles.
Drop-In Replacement Guidance
Formulators switching from AEROSIL OK 520 to GMATT 200 can start at a 1:1 weight replacement. In most solvent-borne clear and pigmented systems, no reformulation is needed — the surface chemistry compatibility is close enough that wetting, anti-settling, and matting behavior remain within specification. Two adjustments to watch: if your system relies on the slightly higher surface area of OK 520 (~170 vs ~140 m²/g), increase GMATT loading by 0.3–0.5% to match target gloss. For waterborne hybrids, evaluate with GMATT WB series instead, as the surface treatment on the 200 series is optimized for solvent polarity. Trial batches at lab scale (500 g) before production commitment.
- Start 1:1 by weight — No binder or additive changes needed in most alkyd, PU, and epoxy systems.
- Adjust +0.3–0.5% if needed — Only required when targeting sub-10 GU gloss in systems previously optimized for OK 520’s higher surface area.
- Use GMATT WB for waterborne — The 200 series surface treatment is solvent-optimized; waterborne systems need the WB series for proper dispersion.
Pricing & Supply Chain Considerations
AEROSIL OK 520 typically prices at $8–12/kg depending on region and volume, with lead times of 6–10 weeks from European production. GMATT 200 series offers a 15–25% cost advantage at $6–9/kg with shorter lead times of 3–5 weeks from Asian manufacturing. For formulators consuming 1–5 MT/month, the annual savings on a full switch range from $12,000–$45,000 depending on loading rates. Supply continuity has been a recurring concern with AEROSIL products — 2024–2025 saw multiple allocation events driven by force majeure at Evonik facilities. GMATT maintains dual-site production capacity, reducing single-source risk.
Specification Comparison Table
Key specifications compared at standard test conditions. Values represent typical ranges from technical data sheets and independent lab verification.
| Property | GMATT 200 Series | AEROSIL OK 520 |
|---|---|---|
| BET Surface Area | 130–160 m²/g | ~170 m²/g |
| Median Particle Size (D50) | 3.5–4.5 µm | 3–5 µm |
| Surface Treatment | Proprietary organosilane | HMDS |
| Hydrophobicity (methanol wettability) | ≥40% | ≥40% |
| 60° Gloss at 5% loading (PU) | 8–12 GU | 8–14 GU |
| Thermal Stability | Up to 300 °C | Up to 300 °C |
| Bulk Density | 80–120 g/L | ~50 g/L |
| Price Range (FOB) | $6–9/kg | $8–12/kg |
| Typical Lead Time | 3–5 weeks | 6–10 weeks |
Frequently Asked Questions
Common questions about comparison.
+Can GMATT 200 directly replace AEROSIL OK 520 without reformulation?
Yes, GMATT 200 works as a 1:1 weight replacement in most solvent-borne systems including alkyds, polyurethanes, and epoxies. No changes to binder ratios or additive packages are typically required. Only increase loading by 0.3–0.5% if your target is sub-10 GU gloss.
+What is the price difference between GMATT and AEROSIL OK 520?
GMATT 200 series costs $6–9/kg versus $8–12/kg for AEROSIL OK 520, representing a 15–25% cost advantage. For a formulator using 2 MT/month at 5% loading, annual savings range from $12,000–$45,000 depending on negotiated pricing.
+How does gloss reduction compare between the two products?
Both achieve 60° gloss values of 8–14 GU at 5% loading in polyurethane systems. GMATT 200 tends toward the lower end of that range due to optimized particle morphology, delivering slightly better matting efficiency per unit weight in high-solids formulations.
+Is GMATT 200 suitable for waterborne coatings?
No, GMATT 200 series is optimized for solvent-borne systems. For waterborne formulations, use GMATT WB series instead — it features a different surface treatment designed for aqueous dispersion stability. The hydrophobic treatment on the 200 series will cause dispersion issues in water.
+What particle size should I expect after dispersion?
Both products deliver median particle sizes (D50) in the 3–5 µm range after standard high-speed dispersion. GMATT 200 achieves tighter distribution around 4 µm, which helps ensure consistent film texture and reduces batch-to-batch variation in final gloss readings.
+Are there supply chain advantages to switching to GMATT?
GMATT offers 3–5 week lead times versus 6–10 weeks for AEROSIL OK 520, plus dual-site manufacturing that reduces single-source risk. AEROSIL experienced multiple allocation events in 2024–2025 due to production disruptions at European facilities.
For most solvent-borne coatings, GMATT 200 is a validated drop-in replacement for AEROSIL OK 520 — matching gloss performance at 15–25% lower cost with shorter lead times and dual-source supply security.