2026-04-23
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Tech Guide · Matting Agents How to Select Matting Agents for UV Cure Coatings
100% solid UV systems impose unique constraints that standard silica cannot meet. This guide explains the critical parameters, common failure modes, and grade selection logic for UV wood, floor, and plastic coatings.
UV Coatings Matting Agents Silica Selection Wood Flooring Formulation
Most formulators start with the same silica matting agent across all coating systems. In solvent-based and waterborne…
Most formulators start with the same silica matting agent across all coating systems. In solvent-based and waterborne coatings, this is often acceptable. In 100% solid UV systems, it leads to serious failures.
UV coatings are fundamentally different from solvent-based systems in three ways that directly affect matting agent performance:
All components remain in the film. Silica particles are fully embedded — meaning you need slightly higher loading to achieve the same gloss reduction compared to solvent systems.
UV monomers and oligomers have viscosities far below conventional resins. Standard silica settles rapidly and forms hard, unredispersible cakes within days of storage.
The curing reaction is near-instantaneous. Any wax treatment on the silica surface can migrate to the film surface during this process, creating a "weak boundary layer" that destroys inter-coat adhesion.
Critical failure mode: Standard polyethylene (PE) wax-treated matting agents — widely used in solvent systems — will migrate to the UV film surface during rapid curing. This wax layer prevents subsequent coats from bonding, causing delamination in multi-layer UV wood and floor systems. Never use PE wax-treated silica in 100% solid UV formulations.
When evaluating a silica matting agent for UV cure coatings, four technical parameters determine suitability: 1.…
When evaluating a silica matting agent for UV cure coatings, four technical parameters determine suitability:
This is the most critical parameter in UV systems. The treatment must provide anti-settling performance without using migrating waxes. Look for proprietary organic treatments or specialized non-wax surface modifications that provide steric hindrance against settling while remaining chemically inert during UV cure.
Particle size must be matched to the dry film thickness (DFT) of the coating. A particle protruding above the film surface creates excessive surface roughness; a particle fully buried below the surface contributes little to gloss reduction.
| Dry Film Thickness | Recommended D50 | Typical Application |
|---|---|---|
| 15 – 25 µm (thin) | 7.0 – 7.5 µm | UV spray topcoat, OPV |
| 25 – 30 µm (medium) | 7.5 – 8.0 µm | UV wood topcoat (standard) |
| > 30 µm (thick) | 8.0 – 8.5 µm | UV roller coat, floor primer |
High oil absorption silica (>250 g/100g) drastically increases viscosity in 100% solid UV systems, making roller and spray application impossible. For UV formulations, target an oil absorption of 130 – 220 g/100g to balance matting efficiency with workable rheology.
Rule of thumb: In solvent-based coatings, high oil absorption is acceptable because solvent dilutes the system. In 100% solid UV coatings with no diluent, every gram of oil absorbed directly translates to viscosity increase. Lower oil absorption matting agents allow higher addition rates without rheological problems.
Pore volume (ml/g) governs how much UV monomer/oligomer is absorbed into the silica particle. Excessively high pore volume leads to monomer absorption, reducing cure efficiency at the particle surface and causing soft spots in the cured film. For UV systems, a pore volume of 1.4 – 1.8 ml/g is the appropriate range.
GMATT U800 is engineered specifically for 100% solid UV coatings. It uses a proprietary organic treatment — no PE wax —…
GMATT U800 is engineered specifically for 100% solid UV coatings. It uses a proprietary organic treatment — no PE wax — ensuring zero inter-coat adhesion loss across a wide DFT range.
| Grade | D50 (µm) | Oil Absorption (g/100g) | Pore Volume (ml/g) | Target DFT | Primary Use |
|---|---|---|---|---|---|
| GMATT U800 | 8.0 – 8.5 | 170 – 220 | ≥ 1.4 | > 30 µm | UV roller coat, floor, heavy primer |
GMATT U800: SiO₂ ≥ 99.0%, pH 6.0–8.0, surface treatment: specialized organic (non-wax).
Particle size distribution, oil absorption curves, and application data sheets available on request.
UV wood flooring is the most demanding application in this category. Roller coating lines operate at high speed with thick films (DFT 30–60 µm), and the coating must withstand heavy foot traffic after cure. The matting agent must provide strong matting power, excellent scratch resistance, and robust anti-settling during storage.
Recommended: GMATT U800. The larger D50 (8.0–8.5 µm) is well-matched to thick film DFT, and the controlled oil absorption (170–220 g/100g) prevents viscosity problems in roller coat viscosity ranges.
Furniture and cabinet UV spray topcoats typically run at DFT 20–30 µm. The key requirements are high transparency (no hazing over dark wood grain), efficient gloss control, and stable anti-settling in the low-viscosity spray formulation.
Recommended: GMATT U800. For ultra-thin decorative coatings below 20 µm, use it at the lower end of the dosage range with fine dispersion to keep the matte even.
UV coatings on mobile phone casings, laptop lids, and automotive interior panels require exceptional surface smoothness alongside gloss control. The formulation viscosity is typically very low (reactive diluent-heavy), making anti-settling the primary challenge.
Recommended: GMATT U800. The specialized organic treatment provides steric hindrance that keeps particles soft-settled — easily redispersed with gentle agitation — even in near-water-thin monomer blends.
OPV applications run very thin (DFT 5–15 µm) and require absolute clarity to preserve print colour fidelity. The matting agent must not scatter light or cause haze over process colours.
Recommended: GMATT U800. Use at the lower end of the dosage range (3–5%) and optimise dispersion with high-shear mixing before letdown.
| UV Application | Recommended Grade | Key Reason |
|---|---|---|
| Wood flooring — roller | GMATT U800 | Large D50 matches thick DFT; high scratch resistance |
| Wood topcoat — spray | GMATT U800 | High transparency keeps grain visible; tune dosage for medium DFT |
| Plastic / 3C — spray | GMATT U800 | Strong anti-settling in low-viscosity systems; optimise dispersion |
| OPV packaging | GMATT U800 | Low dosage + fine dispersion to minimise haze on thin films |
| UV floor primer | GMATT U800 | High loading tolerance; robust suspension |
Dosage in UV cure coatings is slightly higher than equivalent solvent-based systems because there is no film shrinkage…
Dosage in UV cure coatings is slightly higher than equivalent solvent-based systems because there is no film shrinkage during cure. In solvent systems, solvent evaporation concentrates the silica particles near the surface, enhancing gloss reduction efficiency. In 100% solid UV, the particles remain exactly where dispersed.
| Target Gloss (60°) | Finish Level | Suggested Dosage (UV) | Equivalent Solvent Dosage |
|---|---|---|---|
| 0 – 5 GU | Dead matte | 8 – 12% | 5 – 8% |
| 5 – 15 GU | Matte | 6 – 9% | 4 – 6% |
| 15 – 35 GU | Satin | 4 – 6% | 2 – 4% |
| 35 – 60 GU | Semi-gloss | 2 – 3% | 1 – 2% |
Dosage is based on total formulation weight. These figures are starting points — actual dosage depends on resin type, film thickness, application method, and cure speed. Always run a dosage sweep (e.g. 4%, 6%, 8%, 10%) when qualifying a new formulation.
Disperse the matting agent in a portion of the reactive diluent (TPGDA, HDDA, or similar) at 2,000–3,000 rpm for 15–20 minutes before adding to the main resin blend. This prevents agglomeration.
Add the pre-dispersion to the main oligomer/resin blend under gentle stirring (500–800 rpm). High shear at this stage can break down the silica particle structure and reduce matting efficiency.
After 24 hours of storage, check for settling. The GMATT UV Series should form a soft, easily stirrable sediment — not a hard cake. If hard settling occurs, increase the fumed silica thixotrope loading by 0.2–0.5%.
Always measure at 60° for matte and semi-gloss finishes. 85° measurement is appropriate only for near-dead-matte finishes below 5 GU. Cure the film fully before measurement — under-cured films give misleadingly low gloss readings.
Problem: Hard cake settling after 1–2 weeks Cause: Insufficient anti-settling treatment or formulation viscosity too…
Cause: Insufficient anti-settling treatment or formulation viscosity too low. Solution: Switch to GMATT UV Series (proprietary organic treatment) and/or add 0.3–0.5% hydrophobic fumed silica (SEMISIL R202) to build a thixotropic network.
Cause: PE wax-treated matting agent migrating to film surface during UV cure. Solution: Replace immediately with GMATT UV Series — non-wax organic treatment does not migrate. No other fix is reliable.
Cause: Oil absorption of matting agent too high for the 100% solid system. Solution: Switch to GMATT UV Series (oil absorption 130–220 g/100g). Reduce loading by 1–2% and compensate with a finer reactive diluent.
Cause: Particle size D50 too large for the actual dry film thickness. Solution: Measure your actual DFT with a film thickness gauge. GMATT U800 (D50 8.0–8.5 µm) is matched to thicker films (DFT > 30 µm); for thinner films, lower the dosage and improve dispersion to keep the matte even.
Cause: Silica refractive index mismatch with resin, or particle size too large scattering visible light. Solution: Reduce dosage and improve dispersion so the particles scatter less visible light. Ensure full UV cure — under-cured films always appear hazy.
Cause: Variable dispersion quality or inconsistent cure energy. Solution: Standardise pre-dispersion procedure. Check UV lamp energy output with a radiometer — degraded lamps give variable cure and variable gloss.
Use our interactive Grade Selector — input your coating system, DFT, and target gloss to get an instant recommendation.
No. Standard PE wax-treated matting agents are incompatible with 100% solid UV systems. The rapid radical cure forces wax migration to the film surface, creating a weak boundary layer that prevents inter-coat adhesion. Always specify a non-wax organic treatment — such as the GMATT UV Series — for UV applications.
In solvent coatings, solvent evaporation concentrates silica particles near the surface, enhancing gloss reduction at lower loadings. In 100% solid UV coatings, no evaporation occurs — particles stay distributed throughout the film depth. Expect to add 1.5–2× the dosage you would use in an equivalent solvent system.
The GMATT UV Series uses a steric-hindrance organic treatment that causes settled particles to form soft, easily redispersible sediment rather than a hard cake. For extreme low-viscosity cases (below 500 cP), also add 0.3–0.5% hydrophobic fumed silica (e.g. SEMISIL R202) to build a weak thixotropic network that suspends the matting agent.
Pre-disperse in reactive diluent at 2,000–3,000 rpm for 15–20 minutes, then add to the main resin blend at low shear (500–800 rpm). Never add dry silica directly to the full oligomer blend — this leads to agglomerates that are impossible to break down without damaging the particle structure.
Minimal effect. The GMATT UV Series is chemically inert to the radical polymerisation process. At typical loadings (5–10%), no measurable change in cure speed is observed. At very high loadings (\>12%), the silica mass may slightly shield photoinitiator from UV irradiation — compensate with a marginally higher photoinitiator level or increased UV dose.
Yes, with caution. The GMATT UV Series performs well in WB-UV systems at pH 6–8. For strongly alkaline WB-UV dispersions (pH \> 9), consider the GMATT WB Series instead, which has a dedicated waterborne-compatible surface treatment and superior stability at high pH.
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