Ultra-Fine Particle Size for 5–15 µm Film Builds
Leather topcoats are among the thinnest functional coatings in the industry, and particle size control is critical. GMATT 240 (d50 4 µm) and GMATT 245 (d50 4.5 µm) are specifically engineered for 5–15 µm DFT PU and NC leather finishes. Their ultra-fine particle size ensures complete submersion within the film at standard loadings of 2.0–3.5 wt%, eliminating surface particle protrusion that would disrupt grain texture, create a chalky touch, or cause transfer marks on adjacent surfaces during flexing.
Zero Wax Contamination at Leather Grain
In conventional wax-treated silica, excess free wax can migrate to the grain surface and deposit white residue — a critical defect in high-end full-grain leather and embossed PU leather. GMATT 240 and GMATT 245 use a controlled wax grafting process that bonds the lubricant firmly to the silica surface, preventing migration under compression or heat (≤80°C), and preserving the natural colour depth and grain definition of the leather substrate throughout the topcoat's service life.
No Hazing on Deep Black and Dark Brown Shades
Dark leather shades amplify any optical defects in the finish. GMATT 240 and GMATT 245 are characterised by an extremely narrow particle size distribution (d90 < 12 µm), minimising the large-particle scattering events that register as a grey haze on dark substrates. The individual particle dispersion promoted by the wax modification eliminates cluster scattering, delivering a clean, flat matte appearance on navy, chocolate, and black leather finishes at 60° gloss targets of 8–20 GU.
Silky Tactile Surface in PU Leather Systems
Beyond optical performance, leather buyers evaluate hand feel. GMATT 245 imparts a characteristically silky, dry-touch surface at 2.5–3.5 wt% loading in PU leather topcoat — softer than the slightly draggy feel produced by untreated silica grades. The wax surface simultaneously reduces the coefficient of friction of the topcoat, improving abrasion resistance in high-wear applications such as automotive seat leather and furniture upholstery.
When to Use GMATT 240/245 for Leather Coatings
The ultra-fine particle size and grain-safe wax treatment of GMATT 240/245 make them the standard for thin-film leather topcoats where grain clarity, tactile quality, and dark-shade appearance are non-negotiable.
| Scenario | Recommended Grade | Target DFT | Loading |
|---|---|---|---|
| PU leather topcoat, dark shades | GMATT 240 / 245 | 8–15 µm | 2.0–3.5 wt% |
| NC-based leather lacquer, clear | GMATT 240 / 245 | 5–12 µm | 2.0–3.0 wt% |
| Automotive interior leather, matte | GMATT 240 | 6–10 µm | 2.0–3.0 wt% |
| Embossed PU leather, grain-safe | GMATT 245 | 8–15 µm | 2.5–3.5 wt% |
| General PU leather topcoat | GMATT 255 / 260 | 15–25 µm | 2.5–4.0 wt% |
Technical FAQ
Leather finishing formulation specifics for GMATT 240, GMATT 245, and the broader GMATT 200 ultra-thin range.
+Why is GMATT 240 preferred over coarser silica in ultra-thin leather topcoats?
At 5–15 µm DFT, particles larger than d50 6 µm protrude above the film surface, creating a rough texture that obscures grain definition and transfers white residue onto the leather grain under flexing. GMATT 240 (d50 4 µm) and GMATT 245 (d50 4.5 µm) remain fully embedded within the thin topcoat film, preserving grain fidelity, providing a silky tactile feel, and eliminating wax contamination at the grain.
+How does GMATT 240/245 avoid hazing on dark leather shades?
Hazing on dark leather is caused by coarse silica particles scattering light at angles detected as a grey veil by the human eye. GMATT 240 and GMATT 245 have a d90 below 12 µm and a very narrow particle size distribution, minimising large-particle scattering. The wax surface modification also reduces agglomeration in solventborne PU, so the silica disperses as individual particles rather than clusters that would amplify haze.
+What loading is recommended for GMATT 245 in PU leather topcoat at 8–12 µm DFT?
GMATT 245 at 2.0–3.5 wt% is the standard formulation window for PU leather topcoats at 8–12 µm DFT targeting 60° gloss of 8–20 GU. For extra-matte effects (60° below 10 GU), loading can be extended to 4.0 wt% provided the DFT is held to at least 8 µm to keep all particles sub-surface. At DFT below 6 µm, switch to GMATT 240 (d50 4 µm) to maintain particle submersion.
+Is GMATT 240 compatible with nitrocellulose-based leather lacquers?
Yes. GMATT 240 is compatible with solventborne NC-based leather lacquers, PU leather finishes, and WAX-modified acrylic topcoats. The wax surface modification does not interfere with NC resin film formation at typical leather application concentrations (2.0–4.0 wt%). For water-based leather topcoats, the GMATT WB Series is the correct choice as its hydrophilic surface modification prevents agglomeration in aqueous media.
+Can GMATT 240/245 be used in automotive interior leather coatings meeting VW or BMW specifications?
GMATT 240 and GMATT 245 are suitable for automotive interior leather finishes targeting 60° gloss of 5–15 GU (instrument panel, seat leather, door panel). They meet the particle-size prerequisites for VW TL 226 and BMW GS 93032 mar-resistance tests. Formulators should verify the complete specification against their 2K PU or radiation-cured binder system, as automotive OEM approval requires full system qualification, not individual component approval.
Recommended Solution
For ultra-thin leather topcoats demanding grain clarity, silky tactile feel, and zero hazing on dark shades, specify GMATT 200 Series — beginning with GMATT 240 or GMATT 245 for DFT below 15 µm.
SEMITECH matrix · co-purchase