How to Choose Matting Agent for Wood Coatings: HMMAT 600 vs 800 Selection Logic

The procurement question

You're formulating a wood lacquer — nitrocellulose, polyurethane, or acid-catalysed alkyd. The customer wants matt finish (20-40 GU at 60°). You can buy "matting silica" from a dozen suppliers. Two visually similar products from East Materials: HMMAT 600 and HMMAT 800. Cost differs by ~15%. Which one?

This is the question we field most often from furniture-coating chemists. The short answer:

• HMMAT 600 for industrial wood applications where inter-coat sandability matters
• HMMAT 800 for consumer-facing decorative wood where burnish resistance matters

Same particle size range (5-12 μm), same loading window (3-8% on resin solids), totally different application driver. Here's the chemistry behind the choice.

What matting silica actually does

Synthetic precipitated silica with controlled 4-12 μm particle size and surface treatment. Particles protrude from the cured coating surface, creating micro-roughness (50-200 nm RMS) that scatters reflected light. Result: visual matt appearance without changing the underlying coating chemistry. The "matt" is purely optical — the film itself remains glossy at the polymer level.

Two side effects matter for procurement:

Side effect 1 — Sandability. When you sand a matt-coated surface for inter-coat preparation, the silica particles act as micro-abrasives that clog sandpaper. The more silica, the faster the sandpaper wears.

Side effect 2 — Burnish (polishing-out). When a coated surface is rubbed (cloth, palm, furniture cleaner, daily wear), the silica particles can deflect or compress back into the matrix. The surface becomes glossy where it used to be matt. Customers complaining about "shiny spots on my matt furniture" are reporting burnish.

Both effects are controlled by silica particle internal structure — and that's where 600 vs 800 diverge.

HMMAT 600 — engineered for sandability

The wax surface treatment is critical. The wax acts as a self-lubricant during sanding — the particle releases from the sandpaper without embedding. Result: 30-40% longer sandpaper life vs untreated silica matting agents, plus less fines generated during sanding (cleaner work environment).

The internal porosity is low because the wax surface treatment partially fills the pore structure. This means HMMAT 600 contributes less to coating viscosity per unit weight, which is good for spray application but limits how much matting effect you get at low loading.

Use HMMAT 600 in: industrial wood furniture lacquer (manufacturing line), where inter-coat sanding is part of the process. Industrial cabinet doors. Door frames. Picture frame manufacture. Standard semi-matt to matt finishes on nitrocellulose lacquer or 2K polyurethane.

HMMAT 800 — engineered for burnish resistance

The high internal porosity is the burnish resistance mechanism. Under abrasive pressure (rubbing), the silica particles compress rather than deflect. After compression, the porous structure springs back partially, maintaining surface micro-roughness. Result: matt appearance persists under daily wear.

The tradeoff: untreated surface means silica particles are sticky during sanding (embed into sandpaper, reduce sandpaper life by ~50%). Higher haze (1.5-2.0%) means HMMAT 800 is not appropriate for high-clarity satin or gloss finishes — only matt and deep-matt.

Use HMMAT 800 in: high-end decorative wood (residential furniture, premium cabinets), where the finished surface is exposed to daily handling. Hotel furniture. High-end retail display fixtures. Bespoke joinery. Premium nitrocellulose or PU matt finishes targeted at consumers.

The selection matrix

Dual-grade formulation tip

Some premium formulations use 70% HMMAT 800 + 30% HMMAT 600 — gets most of the burnish resistance plus moderate sandability. Useful for production lines that occasionally need to sand-rework a coated surface but mostly serve the consumer market.

Substituting from competitor products

If your existing formulation uses:

• Evonik Acematt OK / TS: try HMMAT 600 1:1 (wax-treated, sandable)
• Evonik Acematt 3300 / 3600: try HMMAT 800 1:1 (untreated, burnish-resistant)
• W.R. Grace SYLOID C/RAD: HMMAT 600 substitution; SYLOID-W series correspond to HMMAT 800
• J.M. Huber Zeofree: HMMAT 600 generally; Zeofree XL for burnish-resistance applications

Independent testing on actual customer formulations confirms 1:1 substitution typically gives within ±2 GU sheen at 60° and within ±10% sandability — close enough for production trial without reformulation.

FAQ

What loading gives me 20 GU matt?

In typical nitrocellulose lacquer: 4-5% HMMAT 600 OR HMMAT 800 on resin solids gives ~20 GU at 60°. For 10 GU deep matt: 6-8%. For 30 GU semi-matt: 3-4%. These ranges apply to most binders; UV-cure coatings are slightly less matting-efficient (use 5-6% for 20 GU). Validation testing on your specific formulation is required.

Can I get burnish-resistance AND sandability in one product?

Not with single silica grade. The two properties pull in opposite chemistry directions (porosity + surface treatment). HMMAT 800 has 50% less sand life than HMMAT 600. HMMAT 600 has standard burnish (not premium). The dual-grade approach (70% 800 + 30% 600) is the best compromise.

Do these grades work in waterborne wood lacquer?

Yes, but: wax-treated HMMAT 600 may de-wet in highly hydrophilic waterborne lacquers (look for foaming or fish-eye defects during application). Untreated HMMAT 800 is better-tolerated. For waterborne, prefer HMMAT 800 unless sandability is procurement-critical.

What about HMMAT 400 and 500 in wood?

HMMAT 400 (cost-optimised) gives noticeably lower sheen consistency and lower wash-fastness — fine for low-end wood furniture but not for premium retail. HMMAT 500 (washable grade) is engineered for leather/architectural; in wood it works but gives ~2 GU higher sheen at the same loading vs HMMAT 600. Use HMMAT 500 only if you're cross-using with leather coatings.

Related

• HMMAT® Matting Agents Hub — all 6 series
• Silica Paint Matting Agent for Industrial Coatings — neighboring industrial-paint application
• Coatings Hub Selection Guide — broader coating application overview