Matting Agents and Gloss Modifiers for Plastics: 4 Types, Mechanisms, Dosage and Selection

Matting agents are particles and incompatible polymer phases that roughen a plastic surface on a micro scale, so that light is scattered instead of reflected in one direction and the measured gloss falls, and 4 material types do that job in thermoplastics: synthetic amorphous silica, diatomaceous earth, mineral fillers and polymeric phases. The effect is optical rather than chemical, which is why the same silica that stops two film layers sticking together also flattens the shine on the film. Which of the 4 lowers gloss without taking clarity, impact strength or food-contact status with it?

Matting agents are one of the 6 surface and optical modifiers among the 43 families of plastic additives, and they sit closer to the filler shelf than to the stabiliser shelf: the working materials are minerals and synthetic silicas that are already in the plant for other reasons. That overlap sets the structure of this page. It defines matting and gloss, explains the scattering mechanism, sets out the 4 types with the particle data established for each, gives the dosage practice and the masterbatch arithmetic, names the gloss and haze test standards, states the EU and US food-contact positions, names the producers, and closes with the surface families that a matting agent shares a surface with.

One warning belongs at the top. The matting-agent literature for plastics is thinner than the coatings literature, and our source library holds property and regulatory data for the mineral and silica carriers rather than gloss-unit targets. Every figure below is a value from a primary source. Where a number does not exist in our sources, the text says so instead of estimating it.

Table 1. The 4 matting-agent types at a glance.

Particle and regulatory values come from our source library cards for synthetic amorphous silica, diatomaceous earth, talc and calcium carbonate, with the Union list as consolidated on 16 March 2025. Gloss-unit targets are not established in our sources for any of the 4 types.

What Is a Matting Agent?#

A matting agent is a particle or an incompatible polymer phase added to a plastic compound to lower the gloss of the finished surface, by roughening that surface on a scale of roughly one micrometre so that light which would leave it in a single direction leaves it over a wide solid angle. The additive does not change the colour, the polymer chemistry or the bulk mechanical design of the part. It changes what the surface does to light, and it does that from inside the compound rather than from a lacquer applied afterwards.

Two boundaries are worth setting immediately. A matting agent is not a pigment, because it is not selected for the wavelengths it absorbs, and it is not a coating, because a matt lacquer sits on a finished part and belongs to the coatings trade rather than to plastics compounding. The plastics route replaces a second process step with a dosing step at the extruder, which is the commercial reason it exists. What exactly is the gloss that the additive lowers?

What is gloss, and how is it measured?#

Gloss is the fraction of light that a surface reflects specularly, in the mirror direction, and in plastics it is measured with a gloss meter under ASTM D523 or ISO 2813 at a fixed geometry written into the standard. Because both standards define more than one measurement geometry, a gloss value carries no meaning without the angle at which it was taken, so every result on a specification sheet is quoted together with that angle.

Gloss is not haze and it is not transmittance. Haze is measured under ASTM D1003-21, by hazemeter in Procedure A or by spectrophotometer in Procedure B, and under ISO 14782; above 30 % haze the material counts as diffusing and ASTM E2387 becomes the applicable practice. A matt part therefore carries two numbers: a gloss value from ASTM D523 or ISO 2813, and, for any transparent or translucent part, a haze value from ASTM D1003-21. The definition of gloss as a measured optical quantity is set out on the glossary entry for gloss.

Matting agent, flatting agent or delustrant?#

Four names describe the same function: matting agent, flatting agent, delustrant and gloss reducer, and the choice between them is regional and industrial rather than technical. Flatting agent is the coatings term that has travelled into plastics, delustrant comes from fibre production, and gloss reducer is the descriptive form used in additive catalogues. Low-gloss additive appears as a fifth variant in compounder literature.

The term to keep separate is gloss modifier. A gloss modifier moves gloss in either direction, so it covers both the matting agents described here and the gloss enhancers named below the contextual border of this page.

How Do Matting Agents Work? Micro-Roughness and Diffuse Reflection#

Matting agents work by geometry rather than by chemistry: hard particles of roughly 1 to 40 µm sit at and just under the surface of the cooling polymer, deform the skin that forms against the mould or the chill roll, and convert specular reflection into diffuse reflection. A smooth polymer skin reflects a parallel beam as a parallel beam, which the eye reads as shine. A skin interrupted at intervals shorter than the eye resolves sends the same beam over a wide solid angle, which the eye reads as matt.

Three particle properties drive the result, and our source library records each of them for the silica and diatomite grades used in film:

• Particle size and top cut. Diatomaceous earth filler grades average 4 to 30 µm, while a powder runs from 10 to 200 µm, and a top cut of 44 µm in a 25 µm film is the case where roughening turns into a visible defect.
• Particle shape. The irregular porous discs of diatomite, with an aspect ratio of 2 to 10, roughen a film surface more effectively than the blocky calcium carbonate particle of aspect ratio 1 to 3 at the same loading.
• Hardness. Diatomite sits at Mohs 5.5 to 6 and precipitated silica at Mohs 5.5, hard enough to keep their shape against the melt and hard enough to abrade screws, barrels and dies.

That third property is the cost side of the mechanism. Diatomaceous earth is recorded as abrasive in processing, and its iron oxide content of 0.5 to 2 % can accelerate polymer degradation, so a matting level is a trade between the optical effect and the wear and stability penalty.

Why matting also changes haze, colour and surface feel#

Matting a transparent plastic raises its haze, because the scattering that removes the shine also removes the straight-through path that clarity depends on. The refractive index of the particle decides how large that penalty is: diatomaceous earth has a refractive index close to that of polyethylene, which is exactly why it is usable in film where a higher-index particle at the same loading would cloud the web.

Colour behaves differently again. Colour difference is reported under ASTM D2244-25 in CIELAB and the related colour spaces, and yellowness under ASTM E313-20 (R2025), so a colour match and a gloss target are two separate acceptance criteria measured on two separate instruments. The quantified relationship between a gloss change and the measured colour shift on the same part is not established in our sources.

The 4 Types of Matting Agents for Plastics#

Four material types lower gloss in thermoplastic compounds, and they are listed below in the order of how firmly matting is established as their function, from synthetic amorphous silica to polymeric phases. The first two are documented matting materials with full identity and regulatory data. The third is a filler class whose surface effect appears at loadings chosen for other reasons. The fourth is named in the definition of the family but carries no substance data in our source library.

1. Synthetic amorphous silica: precipitated and fumed grades#

Synthetic amorphous silica, CAS 7631-86-9 and EC 231-545-4, is the reference matting material in plastics, and the precipitated grade is the one for which matting is a recorded function alongside antiblock. Precipitated silica has primary particles of 5 to 100 nm that build agglomerates of 1 to 40 µm, a specific surface area of 5 to 100 m2/g, a density of 1.9 to 2.1 g/cm3, a Mohs hardness of 5.5 and an average pore size above 30 nm. Those agglomerates are the working unit: they sit in the size range that interrupts a polymer skin, and they carry the porosity that keeps the particle light for its volume.

Fumed silica shares the CAS number and the EC number but not the function list. Made by flame pyrolysis of silicon tetrachloride, or from quartz vaporised in a 3,000 °C electric arc, it has non-porous primary particles of 5 to 50 nm, a specific surface area of 50 to 600 m2/g and a bulk density of only 160 to 190 kg/m3, and our source library records its plastics functions as thixotrope in unsaturated polyester and epoxy, reinforcing filler in silicone elastomer and free-flow agent. Matting is not among them, so a fumed grade is specified for rheology and a precipitated grade for surface effect. The two synthetic grades and the separately regulated crystalline forms are compared in full on silica in plastics, and the individual cards are precipitated silica and fumed silica. Two identity points prevent ordering errors: CAS 112926-00-8 and 112945-52-5 are former, grade-specific numbers that still appear on safety data sheets, and crystalline silica is a different material with its own regulatory position.

2. Diatomaceous earth#

Diatomaceous earth, CAS 61790-53-2 for the natural mineral and CAS 68855-54-9 for the soda ash flux-calcined grade, is a fossil diatom sediment of 80 to 90 % silica that is used in plastics as an antiblock, a filler and a matting agent. Its particles are irregular porous discs with an aspect ratio of 2 to 10, a Mohs hardness of 5.5 to 6 and a density of 2 to 2.5 g/cm3, and the mineral carries 2 to 4 % alumina and 0.5 to 2 % iron oxide alongside the silica.

The film dose is documented. Ampacet trials place diatomaceous earth in polyethylene film at 2,500 to 10,000 ppm, which is 0.25 to 1.0 wt%, as an antiblock, and the surface roughness that delivers the antiblock effect is the same roughness that lowers the gloss. Two restrictions come with the mineral: calcined grades can contain crystalline silica, which brings respirable crystalline silica occupational limits of 0.1 mg/m3 in the EU and 50 µg/m3 under OSHA, and the iron content can accelerate polymer degradation. The full identity, dosage and regulatory card is on diatomaceous earth.

3. Mineral fillers used as gloss reducers: talc, calcium carbonate and kaolin#

Mineral fillers lower surface gloss as a consequence of loading levels chosen for stiffness, heat resistance or cost, which makes them gloss reducers by consequence rather than matting agents by specification. Talc is platy, with an aspect ratio of 5 to 40, a particle size of 0.5 to 20 µm, a Mohs hardness of 1 and a typical polypropylene loading of 10 to 40 wt%, where it raises stiffness, heat deflection temperature and nucleation rate while lowering impact strength and antioxidant reserve. Calcium carbonate is blocky, with an aspect ratio of 1 to 3, a particle size of 0.02 to 30 µm and a Mohs hardness of 3 to 4.

The comparison that matters for matting is between shapes at equal loading, and the film data settles it: diatomite roughens more effectively than calcium carbonate because of its irregular shape. In the site-wide filler comparison, gloss reduction is recorded as an established effect for synthetic amorphous silica only; for talc, calcium carbonate and kaolin the gloss effect is reported qualitatively rather than as a measured value, and this page states no number for it. The loading windows, densities and property effects of all 13 filler classes are set out on fillers for plastics, and the platy mineral has its own page at talc in plastics.

4. Polymeric and incompatible-phase matting agents#

Polymeric matting agents are second polymer phases that are deliberately incompatible with the matrix, so that the domains they form break up the smooth skin at the mould wall and scatter light from it. This route is named in the site definition of the family, and it is the route used where a mineral particle is unacceptable, for example because of abrasion, because of a transparency requirement, or because the part is thin enough for a hard particle to become a defect.

Our source library holds no verified chemistry, dosage, supplier grade or regulatory entry for a polymeric matting agent in plastics, so no named product appears here. Anyone specifying this route works from supplier data sheets and requests the compatibility, dosage and food-contact status in writing.

Which Matting Agent Suits Each Polymer and Part?#

The matting agent is chosen by the constraint that is hardest to give up, which is transparency in film, abrasion in a filled compound, food-contact status in packaging and particle size in a thin section. No single material wins on all four. Diatomaceous earth is the film answer because its refractive index is close to that of polyethylene, silica is the answer where a controlled agglomerate size and a clean regulatory file matter, and a mineral filler is the answer where the part is already filled and the matt surface is a welcome consequence.

Four constraints decide the choice in practice:

• Transparency. A transparent or translucent part sets a haze ceiling under ASTM D1003-21, which favours a particle whose refractive index is close to that of the polymer.
• Abrasion and equipment wear. Particles at Mohs 5.5 and above wear screws and dies, so a long production run pushes the selection towards the lowest effective loading.
• Section thickness. The top cut of the grade stays well under the wall or film thickness; a 44 µm particle in a 25 µm film is a hole rather than a matt finish.
• Food contact. A packaging part needs an entry in the Union list under Regulation (EU) No 10/2011 and a route under 21 CFR, which both silica and diatomaceous earth have.

The general procedure for weighing constraints of this kind across a whole additive package is set out under how to select plastic additives.

How to select a matting agent in 6 steps#

Follow the 6 steps below in order, because each one removes candidates that the next step would otherwise have to test. The sequence starts with the acceptance criterion and ends with the trial, which is the only step that produces a gloss number for a specific part.

1. Define the target as a gloss value at a stated measurement angle under ASTM D523 or ISO 2813, plus a haze ceiling under ASTM D1003-21 for any part that transmits light.
2. Check the section thickness and set the maximum acceptable top cut of the grade well below it.
3. Apply the regulatory filter first for food-contact and toy applications, keeping only materials with a Union list entry and a 21 CFR route.
4. Select the particle type from the 4 in Table 1, using refractive index for transparent parts and particle shape for maximum roughening per unit of loading.
5. Set a starting level from the documented film range of 0.25 to 1.0 wt% for diatomite, then bracket it upward and downward.
6. Run the trial and measure, reporting gloss, haze, the wear observed on the tooling and the mechanical properties that the loading affects.

How Much Matting Agent Is Needed? Dosage, Masterbatch and Let-Down#

The documented use level for a particulate matting material in film is 2,500 to 10,000 ppm, equal to 0.25 to 1.0 wt%, from the Ampacet antiblock trials with diatomaceous earth in polyethylene, and no separate gloss-target dosage series exists in our sources for injection moulding, sheet or profile. That single window is the honest answer for film. For a moulded part the level is established by trial against a measured gloss value, because the surface of a moulded part forms against a tool whose own texture contributes to the result.

Minerals and silicas enter the process as a concentrate rather than as a loose powder, for the same three reasons that apply to any fine particle: dust control, dispersion and metering accuracy. The concentrate route and its carrier polymers are described under additive masterbatch, and a matting concentrate is handled exactly as an antiblock concentrate is handled, because the two concentrates can be the identical product sold under two function names.

Dosage arithmetic follows the standard conversions rather than a rule specific to this family. A level quoted in ppm converts to wt% by dividing by 10,000, a level quoted in phr for PVC converts with wt% equal to the phr of the ingredient divided by the total phr and multiplied by 100, and the let-down ratio of a concentrate follows from the active content of the concentrate and the target level in the part. The three conversions are worked through under conversion to wt%, ppm and let-down ratio.

Sourcing note. Matting grades are sold by mineral and silica producers rather than by additive houses, and grade names differ between them. Use the plastic additive supplier finder to request quotes and safety data sheets for a stated particle size, top cut and food-contact status.

How Is a Matt Surface Tested? Gloss, Haze and Roughness#

A matt surface is accepted on two instrumental measurements: specular gloss under ASTM D523 or ISO 2813, and, where the part transmits light, haze and luminous transmittance under ASTM D1003-21 or ISO 14782. Both values are reported with their method and, for gloss, with the measurement geometry. A specification that states a gloss number without an angle cannot be verified.

Table 2. The test methods that decide whether a matting agent has worked.

Standards and editions come from the site testing register. ASTM D1925 was withdrawn in 1995 and is not used for yellowness.

Surface roughness measurement is the third leg of the argument, because gloss is the optical consequence of a topography. Our sources name no roughness standard or roughness target specific to matted plastics, so a roughness parameter written into a specification is agreed between the parties rather than taken from this page. The wider set of methods for additive-dependent properties is indexed under testing plastic additives.

How Are Matting Agents Regulated for Food Contact?#

Both established matting materials are authorised for food-contact plastics in the EU: synthetic amorphous silica holds FCM No 504, Ref 86240, silanated synthetic amorphous silica holds FCM No 87, Ref 86285, and diatomaceous earth holds FCM No 707, Ref 46375 with the soda ash flux-calcined grade at FCM No 734, Ref 46380, all as additives with no specific migration limit. Those entries sit in the Union list of Regulation (EU) No 10/2011 as consolidated on 16 March 2025, under which the generic specific migration limit is 60 mg/kg and the overall migration limit is 10 mg/dm2, or 60 mg/kg for food intended for infants.

One specification point governs silica in particular. The Union list entry for synthetic amorphous silica describes the material as primary particles of 1 to 100 nm aggregated to 0.1 to 1 µm, with agglomerates from 0.3 µm upward, and Article 9(2) of the same regulation allows nanoforms only where they are explicitly authorised in Annex I. A grade that departs from the authorised particle specification therefore falls outside the entry, however similar its chemistry. The instrument itself is explained on EU 10/2011.

The US and REACH positions are listed below, each with the instrument that carries it.

• FDA. Silica is cleared as a colorant for polymers under 21 CFR 178.3297, as a direct food additive under 21 CFR 172.480 and for repeat-use rubber articles under 21 CFR 177.2600. Diatomaceous earth is cleared under 21 CFR 178.3297, under 21 CFR 182.90 as a GRAS filler for paper and paperboard, and under 21 CFR 177.2410 for phenolic resins.
• REACH. Silicon dioxide is registered under EC 231-545-4 with 371 active dossiers, checked in ECHA CHEM on 22 September 2026. Natural diatomaceous earth carries no dossier as an Annex V natural substance, while soda ash flux-calcined kieselguhr, EC 272-489-0, has 19 active dossiers.
• SVHC and POPs. Neither synthetic amorphous silica nor diatomaceous earth is on the REACH Candidate List as of 22 September 2026, and neither is listed under Regulation (EU) 2019/1021 on persistent organic pollutants.
• Occupational limits. Calcined diatomite grades can contain crystalline silica as cristobalite, which brings a respirable crystalline silica limit of 0.1 mg/m3 in the EU and 50 µg/m3 under OSHA. The safety data sheet of the specific grade states whether the limit applies.

Who Makes Matting Agents? Silica and Mineral Producers#

Matting materials come from the silica and industrial-minerals industry rather than from the additive houses that supply stabilisers, and 3 producer groups cover the field. Precipitated silica comes from Evonik, Solvay (Syensqo), PPG and Tokuyama. Fumed silica comes from Evonik, Cabot, Wacker, Tokuyama, OCI, Heraeus, Orisil and Xunyuchem, under the trade lines Aerosil, Cab-O-Sil, HDK, Reolosil, Konasil and Zandosil. Diatomaceous earth comes from Imerys and EP Minerals.

Mineral fillers used for gloss reduction come from the filler producers, among them Imerys, Omya, Minerals Technologies and Huber. No producer in our sources markets a dedicated plastics matting line under a distinct brand, which matches the structure of the family: the material is bought by particle specification rather than by product name. The wider directory of plastic additive manufacturers and suppliers covers the groups named here.

Matting Agent Substances on This Site#

Three substance pages carry the materials used for matting, and all 3 are filed under the filler family rather than under this hub, because matting is a secondary function of each one. That is a deliberate filing decision rather than an omission: the same particle is sold as an antiblock, a filler and a matting agent, and the site keeps one identity page per substance.

Table 3. Matting materials with a substance page.

No substance page yet exists for a polymeric matting agent, because no verified chemistry for that route sits in our source library. The full identity register is the plastic additives database.

Matting Agents Next to Antiblock, Slip, Anti-Scratch and Light Diffusers#

Matting agents share a surface with 7 other additive families, and 2 of them are close relatives: antiblock uses the identical silica and diatomite particles, and light diffusers use the same scattering physics for a different purpose. A matting agent lowers reflected gloss at the outer surface, while a light diffuser scatters transmitted light through the bulk, which is why a lighting cover is matt on the outside and diffusing throughout. The table names the property each neighbouring family sets and how it behaves next to a matting level.

Table 4. The 7 families that share a surface with a matting agent.

Can a matt surface be made without an additive? Mould texture and film processing#

A matt surface is produced without any additive by texturing the tool, which transfers its own roughness to the part, and this route competes directly with a matting agent on every programme. Tool texturing costs nothing per kilogram once the tool exists, keeps the compound unchanged and leaves the regulatory file untouched. It also fixes the finish for the life of the tool and cannot be adjusted by turning a dosing unit.

The additive route wins where the finish changes between production runs, where the geometry cannot be textured evenly, or where the same effect is wanted from a compound that a converter buys rather than moulds. In film, chill-roll and web conditions shape the surface as well, which is why a matting trial on film runs at fixed line settings.

Gloss enhancers and clarifiers: the opposite direction#

Gloss enhancers and clarifiers move the same optical properties in the opposite direction, by smoothing the surface skin or by shrinking the crystalline structures that scatter light inside the polymer. Clarifying agents work in the bulk of a semi-crystalline polymer, where they reduce spherulite size and lower the haze measured under ASTM D1003-21, which is the opposite of what a matting particle does at the surface. The chemistry, dosage and haze data for that route sit on clarifying agents for plastics.

Our sources record no verified chemistry, dosage or supplier grade for a dedicated gloss enhancer in plastics, so that half of the gloss-modifier field is named on this page and not described.

Do matting agents affect recycling and regrind?#

Matting particles stay in the polymer through mechanical recycling, because silica, diatomite and mineral fillers are thermally stable at melt temperature and are not removed by washing or by melt filtration at normal screen sizes. A matt compound therefore keeps part of its matt character in regrind, and the mineral content accumulates when regrind is blended back repeatedly.

Two effects need watching in recycled streams. Abrasive particles keep abrading equipment in each successive pass, and the iron oxide content of diatomaceous earth, at 0.5 to 2 %, can accelerate polymer degradation, which matters more in material that has already been through one or more heat histories. No quantified data on gloss retention or property loss across recycling passes for a matted compound appears in our sources.

What this page does not yet state#

Five values that a formulator reasonably expects are not established in our source library, and they are named here rather than estimated. Naming them is the point of the fact-checking process behind this site.

• Gloss-unit targets for a matt finish in any polymer, at any measurement geometry.
• Dosage series relating matting level to measured gloss for injection moulding, sheet or profile.
• The chemistry, dosage and suppliers of polymeric and incompatible-phase matting agents.
• Market size, growth and pricing for matting agents as a distinct additive class.
• A surface roughness standard or parameter target used specifically for matted plastics.

Matting agent FAQs#

Four questions recur once the material choice is made, and each one has a short and definite answer.

What is the difference between a matting agent and a filler?#

The difference is the purpose of the addition rather than the material: a filler is added for volume, stiffness, density or cost at loadings of 5 to 70 phr, while a matting agent is added for surface optics at a fraction of a per cent. The same talc, silica or diatomite serves either purpose, and a filled compound often needs no separate matting agent because the filler has already roughened its surface.

Does a matting agent weaken a plastic part?#

Matting levels of 0.25 to 1.0 wt% are too low to change the bulk mechanical properties of a part, while the mineral fillers used as gloss reducers, at 10 to 40 wt% in polypropylene, do change them, raising stiffness and heat deflection temperature and lowering impact strength. The second effect belongs to the filler loading rather than to the matting function, and it is designed for on the filler side.

Can a matting agent be used in food-contact plastic?#

Yes for the two established materials: synthetic amorphous silica is authorised under FCM No 504 and diatomaceous earth under FCM No 707, both as additives with no specific migration limit, under Regulation (EU) No 10/2011 as consolidated on 16 March 2025. The grade still meets the particle specification written into the entry, and a nanoform is authorised only where Annex I says so, under Article 9(2).

Is a plastics matting agent the same as a matting agent in paint?#

No. A paint matting agent is formulated for a liquid coating that dries or cures on a substrate, and coatings sit outside the scope of this site, which covers additives used in plastics. The materials overlap, because precipitated silica and diatomite serve both trades, but the grades, the dispersion requirements and the regulatory files differ. A plastics grade is selected for melt processing and for the food-contact entries listed above.