Gloss Too High After Cure? Choosing a Silica Matting Agent by Pore Volume and Surface Treatment-IOTA

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Gloss Too High After Cure? Choosing a Silica Matting Agent by Pore Volume and Surface Treatment

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A coating can have perfect color and still look wrong: the gloss is too high, fingerprints show, and the surface reads "cheap" next to a matte competitor.

The standard fix is a silica matting agent — but the choice is not one-size-fits-all. Grade selection runs through two parameters: pore volume (extinction efficiency) and surface treatment (handling and film properties).

The IOTA matting agent series covers five grades for furniture wood lacquer, film coating, industrial coatings and ink products.

1. What Decides Extinction Efficiency?

Pore volume is the main driver: the more pore volume per gram, the more light-scattering surface the grade delivers at equal loading.

Item	FINE SIL 7516	FINE SIL 7300	FINE SIL 7300A	FINE SIL 7300C	FINE SIL 7300E
Particle size (µm)	3.0–4.0	3.2–4.2	3.2–4.2	3.2–4.2	3.2–4.2
SiO2 (dried), %	≥98	≥98	≥98	≥98	≥98
Oil absorption (cm³/g)	2.4–2.5	3.0–3.3	2.9–3.2	3.2–4.2	3.0–3.5
pH (5% suspension)	6–8	6–8	6–8	6–8	5–8
Moisture, %	≤5	≤5	≤5	≤5	≤5
Loss on ignition, %	≤6	≤6	≤6	≤6	≤6
Pore volume (ml/g)	1.5	1.8	2.0	1.8	1.8
Surface treatment	—	—	special	organic	organic

Typical values; final gloss must be verified by drawing-down each grade in your own binder system.

2. Treated or Untreated?

Untreated grades (7516, 7300) — cost-efficient, strong thixotropy, thickening and anti-sinking behavior.

Treated grades (7300A special, 7300C/7300E organic) — easier dispersion, better handling in high-solids systems, and no negative effect on recoat adhesion or drying of the paint film.

The series shares three stated benefits across grades: excellent transparency, efficient extinction with easy dispersion, and no influence on drying performance or recoating adhesion of the film.

3. How Should You Evaluate?

Fix the target gloss level (60° gloss units) and the loading ceiling your viscosity allows.

Shortlist two grades by pore volume and treatment.

Draw down both at equal loading in your binder; measure gloss after full cure.

Check dispersion quality (agglomerates, haze) and recoat adhesion before scaling up.

FAQ

1. Does a matting agent slow down drying?

No — no influence on the drying performance of the paint film is a stated feature of the series. Verify in your system, especially at high loadings.

2. Which grade for wood lacquer?

Furniture wood lacquer is a stated application for the series; start from the pore volume that matches your gloss target, then confirm transparency and recoat adhesion by test.

Conclusion: gloss control is a selection problem, not a loading problem — pick the grade by pore volume and surface treatment, and confirm with a draw-down.

Related product: Matting agent for coating

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