Masterbatch: 5 Types, Composition, Let-Down Ratios and Selection

Masterbatch is a concentrated mixture of pigment or additive dispersed in a carrier resin and supplied as pellets, typically carrying 40 to 65 wt% active content and added to the base polymer at 1 to 5 %. Five types cover almost every use, and the number that decides whether the finished part is right is the let-down ratio, so how is it set? The let-down ratio is set from the level the part has to reach, and this page gives the arithmetic in both of the conventions the trade uses.

The 5 types are color, white, black, additive and filler masterbatch, and the first three carry pigment while the last two carry a functional additive or a mineral. Supplier pages define those five types and stop there. This page adds the numbers they leave out: both let-down conventions with a conversion table, a worked example tied to ISO 4427 pressure pipe, the carrier melt-index rule, the dispersion and color test battery, a defect table, and the regulatory ceilings that a let-down calculation has to stay under.

What follows runs in the order a formulator meets the subject: what masterbatch is, how it differs from a compound, a dry blend and direct dosing, what it is made of, the 5 types, the product forms it is sold in, the let-down maths, how it is manufactured, how it is selected, how its quality is tested, what goes wrong with it, how the substances inside it are regulated, who makes it, and how it behaves in recycling and in customs classification.

Every figure on this page is checked against primary sources; see our methodology and fact-checking process.

Table T1. The 5 types of masterbatch at a glance.

Active content and let-down values are the sourced ranges in our source library. Where our source library holds no value for a type, the cell says "see hub" rather than an estimate.

What Is Masterbatch?#

Masterbatch is a concentrated mixture of pigments or additives blended and extruded together in a carrier matrix, then pelletised so that a processor can dose a small, accurate quantity into natural resin. The carrier is either a wax or a polymer, and the pigment or additive it holds, the active content, sits at 40 to 65 wt% of the pellet in most grades, with 15 to 80 wt% reached in extreme cases. The concentrate is never used on its own: it is diluted into the base polymer at the processing machine, usually at 1 to 5 % of the blend. The one-word spelling "masterbatch" is standard in technical documents, and the two-word form "master batch" survives as a variant in older specifications and in some trade listings.

Which products are therefore not a masterbatch? A fully formulated compound is not, because it already carries its additives at final level and needs no dilution. A dry blend is not, because its components are mixed as unmelted powder rather than melt-compounded into a pellet. A neat additive is not, because it is the pure substance without a carrier. All three are compared against masterbatch in the next section.

Why do processors use masterbatch instead of neat additives?#

Processors use masterbatch for 5 reasons: dosing accuracy for expensive additives, dust-free handling, a longer shelf life than solvent-based systems, the freedom to combine several concentrates at the machine, and a color or property change without a new resin purchase. Those five advantages are the reason the concentrate route exists at all, and they are described below as general industry practice rather than as measured values.

• Dosing accuracy. An antioxidant or a UV stabilizer is needed at hundreds of parts per million, a quantity no plant weighs reliably as loose powder. Diluting the active into a carrier raises the weighed mass by a factor of 20 to 40 and moves the dose into the accurate range of an ordinary feeder.
• Dust-free handling. Pigment powders and mineral fillers form airborne dust during charging. Pellets do not.
• Shelf life. A pelletised concentrate keeps longer than a solvent-based colorant solution, which loses solvent and separates.
• Combination at the machine. Several masterbatches, for example a black and a slip concentrate, can be metered into the same throat and let down together.
• Change without a resin purchase. A processor stocks one natural resin and changes color or property by changing the concentrate, instead of buying a separate precolored grade for every shade.

Masterbatch vs Compound, Precolor, Dry Blend and Direct Dosing#

An additive reaches a polymer by one of 4 routes: melt compounding into a fully formulated compound, masterbatch let down at the processing machine, dry blending of unmelted powder, or direct dosing of a neat powder or liquid. The four routes differ in where the additive is dispersed and in what the processor actually receives at the gate. A compound arrives as ready-to-process pellets that already contain the full additive package. A masterbatch arrives as a concentrate that still has to be diluted. A dry blend arrives, or is made on site, as a powder mixture that first melts in the processing machine itself. Direct dosing skips the intermediate entirely and meters neat powder or liquid at the throat.

Dispersion quality follows that same order, because dispersion is done by the equipment that has the most mixing energy. A compounder disperses pigment and additive on a twin-screw extruder with controlled residence time, and the compounding route itself is described on plastic compounding. A masterbatch gets the same treatment for its active content, then relies on the processing machine only to distribute the already dispersed concentrate. A dry blend and a direct-dosed powder get whatever mixing the processing screw provides, which is why the dry-blend route is standard for rigid PVC extrusion, where the recipe is written in phr and the melt history is short and tightly controlled. Cost decides between them: compounds suit long runs at a fixed specification, and masterbatch suits frequent color or property changes and small lots, where the cost-in-use of the concentrate is lower than holding a precolored grade for every shade.

Table T2. The 4 routes an additive takes into a polymer.

Is masterbatch the same as precolor?#

No: precolor, also called a precolored compound, is resin that already carries its pigment at final level, while masterbatch is a concentrate that the processor dilutes into natural resin at 1 to 5 %. The practical difference is stock: a precolored compound has to be bought, stored and scheduled per shade, whereas a single natural resin plus a shelf of concentrates covers the same shade range. Precolor buys consistency, because the color was made and checked in one place, and masterbatch buys flexibility, because the shade is decided at the machine.

What Is Masterbatch Made Of? Carrier, Active Content and Plastic Additives#

A masterbatch has 3 essential components: the carrier resin or wax that forms the matrix, the active content of pigment or additive at 40 to 65 wt%, and the dispersing aids that wet the particles and keep them apart. Those three components are weighed against each other in every recipe, because raising the active content lowers the share of carrier available to wet and carry it, and the dispersing aid is what keeps that trade-off workable.

The active content can be any of the plastic additives in this reference, from antioxidants and UV stabilizers to flame retardants and mineral fillers, which is why the composition question has no single answer: a white masterbatch is mostly titanium dioxide, a filler masterbatch is mostly calcium carbonate, and an antioxidant masterbatch is mostly carrier. What stays constant is the structure of the recipe.

Table T3. What is inside a masterbatch.

Masterbatch carrier resins: melt flow, polymer-specific and universal carriers#

The carrier must melt and mix into the base polymer without leaving a separate phase, so it is chosen by compatibility first and by melt flow second. Compatibility is a chemistry question. The carrier list in general industry practice pairs EVA or LDPE with polyolefins and with nylon, polystyrene with ABS, SAN and sometimes polycarbonate, and a wax with anything, which is why a wax carrier is called the universal carrier and is the basis of the grades sold as universal masterbatch. An incompatible carrier does not disperse into the matrix: it stays as a discrete phase that shows up as streaks, as weak weld lines, or as a haze in a clear part.

Melt flow decides the second half of the question, because a carrier that is much stiffer or much runnier than the base polymer will not distribute evenly in the short mixing time a processing screw allows. Ampacet specifies MLDPE or LLDPE below 20 melt index for pipe black masterbatch, a value measured as the melt flow rate (MFR) under ISO 1133 or ASTM D1238, and that restraint keeps the black dispersed and the pipe wall homogeneous under pressure. The same logic runs the other way for thin-wall injection molding, where a higher-flow carrier distributes better in a short shot. Carrier selection by polymer and melt index is treated in full on the page for masterbatch carrier resins.

Table T4. Carrier resin by base polymer.

Active content: how much pigment or additive a masterbatch carries#

Active content runs from about 15 to 80 wt% of the masterbatch, with 40 to 65 wt% covering most color and additive grades. Three published values show where the ends of that range sit in practice. A black masterbatch for pressure pipe carries 35 wt% carbon black as the North American standard, and a study masterbatch used in PE pipe research was built at 40 % carbon black to 60 % carrier. A filler masterbatch runs far higher, at 70 to 85 wt% calcium carbonate in a polyethylene or polypropylene carrier. A carbon-nanotube concentrate runs far lower, at 10 to 20 wt% in the PLASTICYL grades, because nanotube agglomerates are extremely hard to break.

Why does high loading have a ceiling? Two limits close in together. Dispersion quality falls first: Ampacet's pipe guidance states that masterbatches above 40 wt% carbon black should be avoided, because the carrier can no longer wet and separate the aggregates. Melt viscosity rises second: Radebe and colleagues at the University of Pretoria reported in 2022 that a 60 wt% calcium carbonate masterbatch in LLDPE had about three times the melt viscosity of the neat polymer until wax and zinc stearate were added. The term itself is defined under active content in the glossary.

Dispersing agents, waxes and the rest of the masterbatch recipe#

Dispersing agents wet the pigment or filler surface, break up agglomerates and lower the melt viscosity of a highly loaded concentrate, which is why almost every color masterbatch carries one. Three chemistries do most of the work: polyglycerol esters, metallocene polyolefin waxes and metal stearates. Palsgaard supplies Einar 103, a plant-based polyglycerol ester pigment dispersing aid used at 1 to 5 % of the color masterbatch formulation and suitable for PE, PP, PVC, PET and PA. Clariant's Licocene metallocene polyolefin waxes act as dispersion aid and as carrier at the same time, which lets a producer reach higher loadings at lower temperature and lower shear. The wax and ester chemistries are compared on dispersing agents for plastics and masterbatch.

The measured effect is large enough to decide whether a highly filled recipe can be run at all. In the University of Pretoria work on a 60 wt% calcium carbonate masterbatch in LLDPE, adding 3 wt% wax together with 1.0 wt% of a metal stearate brought the melt viscosity back to just above that of the neat polymer, against roughly three times higher without them. The same additives also cut the pressure rise a filtration test records, which is the property a filter pressure value measures.

5 Types of Masterbatch#

The 5 types of masterbatch are color, white, black, additive and filler masterbatch, and the first three are color masterbatches that the trade sells separately because their pigments and loadings differ so much. Titanium dioxide and carbon black are each bought in volumes that justify their own product lines, their own loading conventions and their own quality tests, so a producer's catalogue lists white and black apart from the shade range. Additive and filler masterbatch sit outside color altogether: one delivers a function, the other replaces polymer volume.

1. Color masterbatch#

Color masterbatch carries organic and inorganic pigments, and sometimes polymer-soluble solvent dyes, in a carrier resin, and colored pressure pipe is typically produced at a let-down of 2 to 4 %, which is 49:1 to 24:1. Pigments stay as discrete particles in the melt and give opacity and heat stability; solvent dyes dissolve in the polymer and give transparency. Both classes have a temperature ceiling, and the ceiling is a selection criterion rather than a detail, because a pigment that decomposes at processing temperature changes shade in the part and cannot be corrected downstream.

Ampacet's pipe guidance gives the colored-pipe let-down as 2 % (49:1) to 4 % (24:1), often less for non-pressure pipe. Pigment choice also changes the part's dimensions: in injection-molded polypropylene colored with a green masterbatch at 1 to 5 wt%, flow-direction shrinkage rose by 13.6 to 22.3 % against neat PP with a transparent phthalocyanine masterbatch and by 49.5 to 58.3 % with an opaque chromium and copper oxide masterbatch, as reported in the study indexed at Europe PMC under PMC10298002. Ampacet also notes that metamerism has to be managed when a formula moves from heavy-metal to non-heavy-metal pigments. Which pigment survives which processing temperature is set out on colorants for plastics.

2. White masterbatch#

White masterbatch carries titanium dioxide, the Pigment White 6 that gives plastics their opacity and whiteness, in a polyolefin or polyester carrier. It is used wherever a part has to hide what is behind it: opaque packaging, light-barrier dairy bottles, film, profiles and fibres. The loading of a commercial white masterbatch is not established in this reference, so the figure is given on the white masterbatch page rather than estimated here.

Grade choice inside the white is decided by surface treatment against processing temperature. Ampacet reports that a low surface-treatment rutile suits extrusion above 525 °F (274 °C) but promotes pinking in the presence of phenolic antioxidants, while highly treated weathering grades are poor candidates above 450 °F (232 °C). That is a direct interaction between two masterbatches on the same machine, and it is the reason a white concentrate cannot be specified without knowing the antioxidant package. On regulatory status, titanium dioxide has no harmonised EU classification in force: the General Court annulled the classification on 23 November 2022 and the Court of Justice dismissed the appeals on 1 August 2025. Grades and surface treatments are covered on titanium dioxide in plastics.

3. Black masterbatch#

Black masterbatch carries carbon black, which colors the polymer and at the same time absorbs ultraviolet light, and the North American standard for pressure applications is a 35 wt% loading. That dual function is why black is the highest-volume single concentrate in polyolefins: the same addition that makes a pipe, a cable sheath or an agricultural film black also protects it from photo-oxidation for its service life. Ampacet's pipe guidance sets the let-down for that 35 wt% grade at 5 to 6.5 %, which is 19:1 to 14:1, and states that masterbatches above 40 wt% carbon black should be avoided because dispersion suffers.

Three further specifications travel with a pipe black. The pipe standard ISO 4427, with EN 12201-1 in Europe, requires 2 to 2.5 wt% carbon black in the pipe wall. The carrier is MLDPE or LLDPE with a melt index below 20, so that the black stays dispersed through a thick wall. Dispersion itself is reported per lot on a microdispersion scale of 1 to 5, with 1 the best, assessed on about 1.5 mil polyethylene film. In food-contact use the carbon black also carries a ceiling of its own: it is FCM substance 411 in the EU with a maximum of 2.5 % w/w in the polymer. Particle sizes, UV performance and conductive grades are covered on carbon black in plastics.

4. Additive masterbatch#

Additive masterbatch carries a functional additive rather than a colorant, and the level that matters is the active level it delivers in the part: an antioxidant masterbatch dosed at 2.5 % delivers about 1,000 ppm of active antioxidant, according to Ampacet. That two-step arithmetic is what separates an additive concentrate from a color concentrate in practice. A color is judged on appearance and can be adjusted at the machine until the shade matches. A functional additive is judged on a level in the finished part, in wt% or in ppm, and that level is fixed by the active content of the concentrate multiplied by the let-down, with no visual feedback to correct it.

The range of functions supplied this way is wide. For biaxially oriented polyethylene film, Ampacet's BIAX4CE range covers antiblock, antistatic, antifog, migrating and non-migrating slip, and white, which is a fair picture of what a film line meters at the throat. Typical addition sits inside the general 1 to 5 % band, but each family has its own level, and a masterbatch that delivers the wrong level is a formulation error rather than a cosmetic one. The functional grades by additive family are listed below.

Which additives are supplied as masterbatch?#

Most functional additive families are available as masterbatch, above all the ones dosed at low level in film: antioxidants, UV stabilizers, slip, antiblock, antistatic and antifog additives, plus flame retardants, foaming agents and desiccants. The pattern across those ten families is consistent. A family is supplied as a concentrate when its dose is too small to weigh accurately, when its neat form dusts or cakes, or when it has to be distributed evenly enough to bloom to the surface. Table T5 gives the reason per family and the let-down value our source library actually holds, with the status of every figure named.

Table T5. Additive families supplied as masterbatch.

Values marked as supplier or competitor claims are not independently verified. Where our source library has no masterbatch let-down for a family, the cell says so.

5. Filler masterbatch#

Filler masterbatch carries calcium carbonate or talc at 70 to 85 % in a polyethylene or polypropylene carrier, and it is used to replace polymer volume in carrier bags, refuse sacks, raffia and sheet. It is the only one of the 5 types whose purpose is economic before it is technical, and it is also the only one whose let-down is not a small percentage: the dose follows the filler level the part is specified at, which can run to tens of percent of the blend. Fine ground calcium carbonate has one technical role that no other filler covers, as the stretching phase that opens the pores in breathable microporous film. The filler chemistries themselves are compared on fillers for plastics. Sodium sulfate is sold in South East Asia under the name transparent filler masterbatch, and it belongs to the same page.

High mineral loading is bought at the cost of melt viscosity, and the recipe has to pay it back. Radebe and colleagues at the University of Pretoria reported in 2022 that a 60 wt% calcium carbonate masterbatch in LLDPE showed about three times the melt viscosity of the neat polymer, and that 3 wt% wax plus 1.0 wt% zinc stearate restored the melt viscosity to just above the neat value. That pairing of a wax with a metal soap is the standard answer in highly filled concentrates, and it is the reason a filler masterbatch data sheet lists a lubricant package alongside the mineral content and particle size. CaCO3 content, particle size and carrier specifications are treated on the filler masterbatch page.

Masterbatch Product Forms: Pellets, Micro-Pellets, Liquid Color and Paste#

Masterbatch is supplied in 5 forms: standard pellets, micro-pellets, liquid color, paste for PVC plastisols, and dry color, which is pigment blended with a dispersant rather than melt-compounded. Two further delivery forms sit next to them in a colorant catalogue without being masterbatch at all: neat pigment powder, and pigment preparations, which are pigments predispersed at 40 to 70 % on a wax or a polymer but not pelletised into a finished concentrate. Powders, pastilles and dust-free blends are compared under additive product forms.

Form decides the dosing equipment, and the dosing equipment decides the changeover time. Standard pellets are metered by a gravimetric or volumetric feeder and are the default for every process. Micro-pellets do the same job with better distribution in a short shot, which matters in thin-wall molding where a standard pellet may not see enough mixing before the gate. Liquid color is pumped by a peristaltic pump, which gives highly accurate dosing and quick color changes, at the cost of a pump that has to be cleaned. Paste is stirred into a PVC plastisol, and dry color is tumble-blended with the resin, which removes the compounding step and its cost but gives weaker dispersion and brings dust back into the plant. Pump dosing and color-change times are treated on liquid color concentrates.

Table T6. The 5 masterbatch product forms.

What Is a Let-Down Ratio and How Do You Calculate It?#

The let-down ratio is the proportion of masterbatch added to natural resin, and it decides the additive level in the finished part: the final level equals the masterbatch active content multiplied by the masterbatch fraction of the blend. That single multiplication is the whole of the arithmetic, and it is also the reason a let-down ratio is never a free choice: it is fixed by the level the part has to reach and by the strength of the concentrate available.

The same formula runs backwards when the target level is known and the let-down is the unknown, which is the normal case in a specification. Any dose can be checked in both conventions with the let-down ratio calculator, and the four sections below give the conventions, a worked example against a pipe standard, the typical ranges by type, and how the dose is actually metered at the machine.

The two let-down ratio conventions: percentage and ratio#

The same dose is written in 2 ways: as a percentage of the blend, such as 5 %, or as a ratio of resin to masterbatch, such as 19:1, and Ampacet uses both in a single sentence. The conversion rule is short. A ratio of n:1 means 1 part masterbatch to n parts natural resin, so the masterbatch share of the blend is 1/(n+1). At 19:1 that is 1/20, which is 5 %. At 14:1 it is 1/15, which is 6.67 %, and the industry writes it as 6.5 %. That rounding is worth stating openly rather than hiding, because a specification written as "6.5 % or 14:1" contains a small internal inconsistency that a strict calculation will surface.

A third convention exists outside polyolefins. PVC and rubber recipes are written in PHR (parts per hundred resin), where every ingredient is counted against 100 parts of polymer rather than against the total blend, so a phr figure is always slightly larger than the corresponding wt% of the whole compound. Wikipedia's worked example of the percentage convention, 25 kg of masterbatch per tonne of base polymer, converts to 2.5 %, which is 39:1.

Mini-table. Ratio, percentage and kilograms per tonne.

Worked example: black masterbatch for an HDPE pressure pipe#

A PE100 pressure pipe has to contain 2 to 2.5 wt% carbon black under ISO 4427, and the standard 35 wt% black masterbatch reaches that level at a let-down of 5.7 to 7.1 %, which is about 16.5:1 to 13:1; Ampacet's published 5 to 6.5 %, which is 19:1 to 14:1, delivers only 1.75 to 2.28 % and touches the band only at its top. The four steps below show how that specification is read from the standard down to the feeder setting.

1. Read the requirement. ISO 4427, with EN 12201-1 in Europe, asks for 2 to 2.5 wt% carbon black in the pipe wall. This is the level in the finished part, not in the concentrate.
2. Take the standard masterbatch. Ampacet's pipe guidance names 35 wt% carbon black as the North American industry standard for pressure applications, and states that masterbatches above 40 wt% carbon black should be avoided.
3. Calculate the let-down. Dividing the target by the active content gives 2.0 / 35 = 5.7 % at the bottom of the band and 2.5 / 35 = 7.1 % at the top, which is about 16.5:1 to 13:1. Ampacet's published range of 5 to 6.5 %, which is 19:1 to 14:1, delivers about 1.75 to 2.28 % carbon black and therefore reaches the standard band only at its upper end.
4. Check the rest. The carrier has to be MLDPE or LLDPE below 20 melt index, dispersion has to be rated on the 1 to 5 microdispersion scale for every lot, and the loading of the concentrate has to stay at or under 40 wt%.

The same four steps apply to any specification that names a level in the part rather than a dose at the machine. The full pipe additive package is set out on additives for plastic pipes.

Typical let-down ratios by masterbatch type#

Most masterbatches are let down at 1 to 5 % of the blend, and the exceptions are the highly loaded pipe blacks at 5 to 6.5 % and filler masterbatch, whose dose follows the target filler level in the part. The table below gives every let-down value our source library holds, with its source and its verification status, because several figures in circulation come from supplier marketing pages rather than from a standard or a study.

Table T7. Typical let-down ratios by masterbatch type.

How masterbatch is dosed at the machine#

Solid masterbatch is metered into the resin stream by a feeder at the throat of the extruder or molding machine, while liquid color is pumped in by a peristaltic pump. The feeder route runs in two ways. A volumetric feeder turns a screw at a set speed and delivers a volume per unit time, which holds only as long as the bulk density of the pellets holds. A gravimetric feeder weighs what it delivers and corrects itself, which removes the bulk-density error at the cost of a load cell and its calibration. No feeder accuracy figures and no volumetric-versus-gravimetric tolerance comparison are established in this reference, so neither route is given a tolerance here.

Two practical points follow from the dosing arrangement rather than from the equipment. Several concentrates can be metered into the same throat and let down together, for example a black and a slip masterbatch on the same film line, which is one of the reasons the concentrate route exists. And the dose has to be checked against the blend, not against the resin alone, because a ratio convention counts parts of resin while a percentage convention counts the whole blend. Target levels by additive family are collected under additive dosage levels.

How Is Masterbatch Made? Compounding, Split Feeding and Pelletising#

Masterbatch is made in 5 steps: weighing, feeding, melt dispersion on a twin-screw extruder, filtration and pelletising, and lot testing before release. The production line is a compounding line, and the only thing that distinguishes it from any other compounding line is the concentration it has to handle: a 60 wt% mineral or a 35 wt% carbon black loading is far outside the range a finished compound ever sees, so feeding and dispersion are designed around that loading rather than around throughput.

1. Weigh the carrier, the active content and the dispersing aids against the recipe.
2. Feed them into the extruder, either as a premix or by split feeding.
3. Disperse the active content in the melt on a twin-screw extruder, breaking agglomerates down to primary particles.
4. Filter the melt through a screen pack and pelletise it, by strand cutting or under water.
5. Test every lot for dispersion, color and active content before release.

The feeding step is where the two production routes separate, and Coperion describes both. In the premix route, all components are premixed homogeneously and the mixture is fed by a volumetric feeder into the main intake. In the split-feed route, the polymer pellets go into the main feed and the pigments are fed by a twin-screw side feeder downstream of the melting zone, so that the active content meets an already molten carrier. The stated advantage of split feeding is gentle wetting of the pigments and fewer agglomerates, because the pigment is never dragged through the solids-conveying and melting zones where it can be compacted rather than dispersed. Side feeding and screw design are treated on twin-screw compounding.

Dispersion energy is the variable that a customer feels last and most expensively. Ampacet lists poor dispersion caused by insufficient energy in concentrate production among the sources of gels in polyethylene film, which means a dispersion failure at the masterbatch plant surfaces as a defect in a film converter's product, several weeks and one supply chain away. Highly filled recipes need the wax and metal-soap package described above for the same reason: without it the melt viscosity at 60 wt% mineral is roughly three times that of the neat polymer, and the extruder cannot deliver the shear the dispersion needs.

How Do You Select a Masterbatch? 7 Steps and Cost-in-Use#

Select a masterbatch in 7 steps: define the level it must deliver, match the carrier, check the processing temperature, set the active content and let-down together, screen the regulatory ceiling, check interactions, then compare cost-in-use and run a trial. The order matters, because each step constrains the next, and a concentrate chosen on price alone usually fails at step 2, step 3 or step 6.

1. Define what the masterbatch must deliver in the part, as a level in wt% or ppm rather than as a dose. A pipe specification asks for 2 to 2.5 wt% carbon black in the wall, not for a feeder setting.
2. Match the carrier to the base polymer and its melt flow. EVA or LDPE for polyolefins and nylon, PS for ABS and SAN, a wax where the resin is mixed or unknown, and below 20 melt index for a pipe black carrier.
3. Check the processing temperature against the heat stability of the pigment or additive. A low surface-treatment rutile suits extrusion above 274 °C, while a highly treated weathering grade should not be specified above 232 °C.
4. Set the active content and the let-down ratio together. A stronger concentrate at a lower let-down and a weaker one at a higher let-down reach the same level in the part, and they differ in dispersion, in feeder accuracy and in cost.
5. Screen the regulatory ceiling for the end use. Carbon black in a food-contact article is capped at 2.5 % w/w of the polymer, and cadmium pigments are restricted in most plastics under REACH.
6. Check interactions with the rest of the additive package. A low-treatment rutile promotes pinking with phenolic antioxidants, and a combined antiblock and fluoropolymer processing-aid masterbatch can give worse antiblock efficiency in blown film.
7. Compare cost-in-use, not price per kilogram, and confirm the choice by a trial on the production line, at production speed.

The same 7-step logic for any additive is set out on how to select plastic additives. Cost-in-use is the masterbatch price multiplied by its let-down fraction, so a stronger masterbatch at a lower let-down can be cheaper per part even when it costs more per kilogram, and tinting strength is the property that makes that comparison possible for colorants. Two concentrates can be compared directly with the additive dosage and cost-in-use calculator.

How Is Masterbatch Quality Tested?#

A masterbatch is tested for 4 things before it is released: dispersion, color, heat stability and active content. Those four properties map onto a published test battery, and the battery matters more for a concentrate than for a compound, because a defect concentrated at 40 to 65 wt% is diluted into thousands of parts before anyone sees it. The full method set is collected on dispersion testing of pigments and masterbatch.

Table T8. The masterbatch test battery.

Dispersion: filter pressure value, film test and ISO 18553#

Dispersion is the single quality that decides whether a masterbatch performs, and it is measured by pushing a diluted sample through a screen pack and recording the pressure rise per gram of pigment. That test is the filter pressure value, standardised in the EN 13900 series as EN 13900-5, and it is reported in bar per gram of pigment. A fibre grade, where a single agglomerate can break a filament at a spinneret, is held below 1 bar per gram. The number is a direct proxy for what an agglomerate does in a customer's process: it blocks a filter, raises head pressure and shortens the screen-change interval.

Two visual methods sit alongside the pressure test. The film test in EN 13900-6 presses a diluted sample into a thin film and counts what is visible in it, and a black masterbatch is rated on a microdispersion scale of 1 to 5, with 1 the best, on about 1.5 mil polyethylene film, with the rating reported for every lot. For pipe, ISO 18553 counts carbon black and pigment agglomerates on microtome slices cut from the wall, with ASTM D3015 and ISO 11420 as alternative methods, and a pipe grade is normally held at grade 3 or better. The three methods are complementary rather than interchangeable: the pressure test finds what blocks a filter, the film test finds what is visible, and the microtome count finds what sits inside a thick wall.

Color: Delta E, metamerism and heat stability#

Color is compared as a difference value, dE*ab, between the sample and the customer standard, measured under a defined illuminant and observer. ASTM D2244 sets out the calculation of that difference and of the CMC and CIEDE2000 alternatives, and the pass value is set by the customer rather than by the standard, because the tolerance that matters on a bottle closure is not the tolerance that matters on a pipe. CIELAB, dE and metamerism are explained on color measurement and matching.

Two effects complicate the comparison. Metamerism is the case of two colors that match under one light source and fail to match under another, and Ampacet notes that it has to be addressed when a color masterbatch is reformulated from heavy-metal to non-heavy-metal pigments, because the new pigment set rarely has the same spectral curve as the old one. Heat stability is the second: a colorant is step-tested in an oven or on an extruder, with EN 12877-2 as the method, and a commonly used criterion is a dE*ab of 3 or less after 5 minutes at the test temperature. A colorant that passes at one temperature and fails 20 °C higher is a real risk on a line that runs several products.

What Goes Wrong with Masterbatch? Gels, Streaks, Warpage and Discoloration#

Six problems account for most masterbatch complaints: gels and unmelts, color streaks, shade drift and metamerism, pigment-induced warpage, pinking or yellowing of white parts, and additive interactions at the surface. Five of the six are traceable to a decision made before the concentrate ever reached the processing machine, which is why the defect table below names the cause in the concentrate rather than the symptom on the line. Causes and fixes for the first of them are set out on gels and fisheyes in plastic film.

Gels in polyethylene film come from three sources according to Ampacet: degraded or crosslinked polymer, un-melted resin or concentrate, and poor dispersion caused by insufficient energy in concentrate production. The third source is the one a converter cannot fix, because the agglomerate was already there in the pellet. Pinking and yellowing of white parts have a similarly upstream cause: a low surface-treatment rutile promotes pinking in the presence of phenolic antioxidants, and Ampacet lists over-oxidation, pigment interaction, cardboard yellowing and gas fading by nitrogen oxide gases as the discoloration mechanisms behind phenolic antioxidants. Pinking and gas fading are treated on why plastics turn yellow or pink.

Warpage is the defect that surprises formulators most, because it comes from the pigment rather than from the mold. In injection-molded polypropylene colored with a green masterbatch at 1 to 5 wt%, flow-direction shrinkage rose by 13.6 to 22.3 % against neat PP with a transparent phthalocyanine masterbatch and by 49.5 to 58.3 % with an opaque chromium and copper oxide masterbatch, in the study indexed at Europe PMC as PMC10298002. The shrinkage data are collected on pigment-induced warpage. The last two entries in the table are viscosity and surface effects: a highly filled concentrate raises melt viscosity roughly threefold at 60 wt% mineral without a lubricant package, and a combined antiblock and fluoropolymer processing-aid masterbatch can give worse antiblock efficiency in blown film than the two delivered separately.

Table T9a. Six masterbatch defects, their cause and the fix.

How Is Masterbatch Regulated?#

A masterbatch is not regulated as a product: the rules apply to the substances it carries and to the level they reach in the finished article, which is why a let-down calculation is also a compliance calculation. No instrument in the EU or the US restricts concentrates as a category. What they restrict is a pigment, a stabilizer or a heavy metal, expressed either as a maximum use level in the polymer or as a migration limit from the finished article, and both of those are read after dilution, not before it.

The three frameworks that reach a masterbatch in practice are food contact, chemical restriction and consumer-product law. Regulation (EU) No 10/2011 governs plastic food-contact materials with a generic specific migration limit of 60 mg/kg, an overall migration limit of 10 mg/dm2, and 60 mg/kg for food intended for infants, plus a functional-barrier limit of 0.01 mg/kg. In the US, 21 CFR 178.3297 "Colorants for polymers" is the clearance route for colorants in food-contact polymers. Restriction under Regulation (EC) No 1907/2006 (REACH) reaches the pigments directly, through Annex XVII and through the Candidate List. The two sections below take food contact and restricted pigments in turn.

Food-contact masterbatch: EU 10/2011 and FDA 21 CFR 178.3297#

In the EU, colorants are not on the Union list of Regulation (EU) No 10/2011 except for named entries such as carbon black, which is FCM substance 411 with a maximum use level of 2.5 % w/w in the polymer. That entry also sets two purity conditions on the carbon black itself: benzo(a)pyrene at most 0.25 mg/kg of carbon black, and toluene extractables at most 0.1 % measured by ISO 6209. No specific migration limit applies to it. The Union list and the migration limits are set out on EU 10/2011.

The US route is separate and its numbers are its own. Under 21 CFR 178.3297, high-purity furnace black is limited to 2.5 % by weight of the polymer, with polycyclic aromatic hydrocarbons at most 0.5 ppm and benzo(a)pyrene at most 5.0 ppb. The 21 CFR sections are mapped on FDA food contact rules, and the agency does not approve masterbatch as a product: a substance is either cleared under a regulation, covered by a food contact notification, or not authorised for the use. The compliance check that ties this section to the let-down maths is simple and worth running on every food-contact black. A 35 wt% carbon black masterbatch let down at 6.5 % puts about 2.3 % carbon black into the part, which sits under the 2.5 % w/w ceiling. The same masterbatch let down at 8 % would put 2.8 % into the part and would breach it, which is why the let-down ratio and the regulatory ceiling are checked in the same calculation.

Restricted pigments and heavy metals in masterbatch#

The restrictions that reach a masterbatch are the ones on its pigments: cadmium pigments, lead chromates and a small group of classified substances. Four entries carry most of the compliance load for a color concentrate, and entry 23 and the other restrictions are explained on REACH Annex XVII restrictions.

• Cadmium. Annex XVII entry 23 limits cadmium to below 0.01 % by weight of the plastic material in the listed polymers, and it names coloured masterbatch in LDPE as an explicit exception to that limit for LDPE. The same entry allows recovered rigid PVC to carry up to 0.1 % cadmium in listed building applications.
• Lead chromates. Lead sulfochromate yellow, Pigment Yellow 34 (CAS 1344-37-2), and lead chromate molybdate sulfate red, Pigment Red 104 (CAS 12656-85-8), are on the REACH Candidate List.
• Carbon black. Carbon black is listed under California Proposition 65 for airborne, unbound respirable particles, with a listing date of 21 February 2003 on the OEHHA Proposition 65 list, and it is classified by IARC in Group 2B.
• Titanium dioxide. Titanium dioxide has no harmonised EU classification in force, following the General Court annulment of 23 November 2022 and the dismissal of the appeals by the Court of Justice on 1 August 2025.

Every listed pigment is collected on the SVHC Candidate List page, which is the reference to check before a shade is specified for a market where an Annex XIV authorisation or a Candidate List communication duty would apply. The practical rule for a formulator is the same as for food contact: the restriction is written against the plastic material, so it is the concentration after let-down that has to be tested against it, and a Candidate List substance triggers a communication duty at 0.1 % w/w of the article regardless of how it got there.

Who Makes Masterbatch? Market and Suppliers#

The largest masterbatch producers are Avient, Ampacet, Tosaf and Cabot, alongside regional compounders in India, Vietnam, Egypt and Turkey that dominate the filler-masterbatch trade. Published masterbatch market sizes differ widely between analyst houses and none of them is verified here, so this page gives producers and structure rather than a number. Size and producer shares are treated on the masterbatch market page.

The structure of the industry has two layers. The first is a small group of global producers with full color and additive portfolios, their own pigment dispersion technology and food-contact documentation, which is the group Table T10 lists. The second is a large population of regional producers that compete on filler masterbatch and commodity blacks, where freight cost against a low-value product favours local supply. Company profiles are in the directory of masterbatch manufacturers, and the largest single corporate event in the recent history of the sector is Avient's acquisition of Clariant's masterbatch business in 2020 for about USD 1.6 billion, after which PolyOne renamed itself Avient.

Table T10. Masterbatch producers.

All 11 Masterbatch Pages on This Site#

This reference holds 11 masterbatch pages: the 5 types, 2 carrier and form pages, the manufacturing page, and 3 pages for specific functional masterbatches. The table lists them in the same type order used throughout this page, and says which are live and which publish later.

Table T11. All 11 masterbatch pages.

Masterbatch, Recycling and Trade#

The choices made in a masterbatch outlive the part: a black pigment decides whether the packaging can be sorted, and a filler or a pigment decides what the recyclate can be used for. That is the point at which a concentrate stops being a processing decision and becomes a design decision, because neither the sorting line nor the recompounder can undo a pigment choice made years earlier. The whole design-for-recycling picture is on design for recycling. The three questions below cover the two recycling cases and the customs question that arrives with every export shipment.

Do black masterbatches stop plastic being sorted for recycling?#

Yes for conventional blacks: carbon black absorbs the near-infrared light that sorting lines use, so a carbon-black-pigmented part is not detected and goes to the residue stream. Near-infrared sorters identify a polymer from the reflected spectrum, and a carbon-black-pigmented surface returns almost nothing to the detector, which means the object is classified as unidentified regardless of what polymer it actually is. The consequence is economic rather than technical: a black bottle or tray made of perfectly recyclable HDPE or PP leaves the line with the residue.

The answer is a black that is detectable in the near infrared. Ampacet's REC-NIR-BLACK is one such product and is COTREP-certified for polypropylene and HDPE rigid packaging, which means a French packaging assessment body has confirmed that packaging colored with it passes through sorting. Carbon-black-free alternatives are set out on NIR-sortable black colorants.

Can masterbatch be used with recycled resin?#

Yes, and recyclate is one of the places where masterbatch does the most work, because it is the route by which restabilizing antioxidants, desiccants and odour absorbers are added back into a used polymer. A polymer that has already been through one melt history has consumed part of its stabilizer package, and restabilization with antioxidant blends at 0.1 to 0.3 wt% is what allows a recycled polyolefin to be processed again without a further drop in melt strength and color.

Two further concentrates address defects specific to recyclate. Desiccant masterbatch binds residual moisture, which otherwise appears as lensing, voids and bubble breaks in film: Plastiblends gives a dosing rule of 1 % masterbatch per 0.15 % moisture, with a general range of 1 to 5 % and use within 16 to 24 hours of opening the bag, and Mascom publishes the same general range. Odour adsorbents address the second complaint, with 4 wt% zeolite reported to cut odour intensity by 45 %. The full restabilization package is set out on additives for recycled plastics.

What is the HS code for masterbatch?#

Masterbatch has no single customs code: the classification follows the carrier polymer and the active content, so a filler masterbatch and a color masterbatch can fall in different headings. No HS code for masterbatch is established in this reference, and none is stated here, because a wrong code on a declaration is a customs liability rather than a rounding error. Classification and duties are covered on plastic additive trade: HS codes and tariffs.