Deep Matt (≤5 GU at 60°): Maximum Extinction
Achieving below 5 gloss units at 60° demands large-particle precipitated silica (D50 8–12 µm) at high loadings of 4–6% by weight. GMATT 600 Series grades are purpose-built for this range, delivering aggressive light scattering without excessive viscosity build. At these loadings, expect a measurable drop in abrasion resistance — typically 15–20% versus the clear coat baseline.
Particle size is the primary lever. Grades below 6 µm D50 cannot reach ≤5 GU at reasonable loadings. If your system is solventborne alkyd or polyester, start trials at 5% loading and adjust in 0.5% increments. For waterborne systems, pre-dispersion at 20–25% solids prevents agglomeration that would push gloss back up.
Matt (5–15 GU at 60°): The Workhorse Range
The 5–15 GU window covers the majority of industrial and architectural matt specifications. Gel-type silica grades with D50 5–8 µm — such as GMATT 100 or GMATT 200 Series — hit this range at moderate 2.5–4% loadings while preserving good film transparency.
Formulators targeting the lower end (5–8 GU) should select GMATT 200 grades with higher oil absorption (≥200 mL/100 g), which trap more resin and scatter light more effectively. For the upper band (8–15 GU), standard GMATT 100 grades at 2–3% loading deliver consistent results across epoxy, PU, and acrylic resin systems. See our resin-system compatibility guide for grade-by-resin recommendations.
Satin (15–40 GU at 60°): Controlled Haze
Satin finishes require fine-particle silica (D50 3–5 µm) at low loadings of 1–2.5%. The challenge is consistency — small loading variations cause visible gloss swings. GMATT 300 Series grades with narrow particle-size distribution (span <1.8) minimize batch-to-batch variation.
For UV-curable satin finishes, standard thermal-silica grades settle during the short open time before cure. GMATT UV Series grades carry surface treatment that maintains suspension in acrylate oligomers, keeping gloss uniform across the film. At 1.5–2% loading, they reliably hold 20–30 GU in LED and mercury-lamp cure lines.
Why Measurement Geometry Changes Your Grade Choice
Gloss specs on the same coating can read dramatically different at 20°, 60°, and 85° geometries. A film reading 10 GU at 60° might show 2 GU at 20° and 35 GU at 85°. If your customer specifies 20° gloss below 5, you need a coarser grade and higher loading than the 60° number alone would suggest.
Always confirm which geometry the spec calls for before selecting a grade. Our gloss measurement fundamentals page covers the ISO 2813 method and angle-selection logic. Misreading the geometry is the most common cause of failed matting trials — it shifts your effective target by one full bracket.
Frequently Asked Questions
Common questions about selection guide.
+What matting agent loading is needed for below 5 GU gloss?
Reaching below 5 GU at 60° typically requires 4–6% loading of a large-particle precipitated silica with D50 of 8–12 µm. Start trials at 5% and adjust in 0.5% increments. Finer grades cannot reach this range at practical loadings.
+Can I use the same matting agent for both matt and satin finishes?
Not optimally. Matt finishes (5–15 GU) use D50 5–8 µm grades at 2.5–4%, while satin (15–40 GU) needs D50 3–5 µm at 1–2.5%. Using a matt-grade silica at reduced loading for satin causes inconsistent haze and poor batch reproducibility.
+How does particle size affect matting efficiency?
Larger particles scatter more light per unit loading, producing lower gloss. A D50 10 µm grade reaches 5 GU at 4% loading, where a D50 4 µm grade would need over 8% — impractical due to viscosity build and film defects. Choose particle size to match your target bracket.
+Why does my matting agent perform differently in UV coatings?
Standard silica settles during the short open time before UV cure, creating uneven gloss. UV-specific grades like GMATT UV Series have surface treatments that maintain suspension in acrylate oligomers, delivering uniform matting across the cured film.
+Does gloss measurement angle matter when choosing a matting agent?
Yes — it shifts your effective target by a full bracket. A coating at 10 GU (60°) reads about 2 GU at 20°. If the spec calls for 20° measurement, you need a coarser grade and higher loading than the 60° number suggests. Confirm geometry before selecting.
+How do I reduce batch-to-batch gloss variation in satin finishes?
Use silica grades with narrow particle-size distribution (span below 1.8) and tight loading control at ±0.1%. GMATT 300 Series grades are engineered for this consistency. Pre-disperse at controlled shear to avoid agglomerate breakdown that shifts the effective D50 between batches.
Match particle size to your gloss bracket first, then fine-tune with loading percentage. Deep matt needs D50 ≥8 µm at 4–6%; matt needs 5–8 µm at 2.5–4%; satin needs 3–5 µm at 1–2.5%.