Processing Lubricants for Plastics: 5 Classes, Internal and External Lubricants, Dosage and Selection

Processing lubricants are waxes, metal soaps, fatty acids, esters and amides that lower friction during melt processing, either between the polymer chains and particles (internal) or between the melt and hot metal (external), at 0.1 to 3 wt% of the finished plastic. Rigid PVC needs them most, because it carries a high melt viscosity and a thermal window so narrow that it starts losing hydrogen chloride at 100 to 120 °C, well below the temperature at which it would flow freely, so which lubricant does which job? Across all polymers the family takes about 2 % of global plastic additive consumption by weight.

Processing lubricants are one of the 43 families of plastic additives catalogued on this site, and they sit in the processing-modifier group beside processing aids, mould release agents, slip agents and antiblock additives. This page covers only the lubricants compounded into the plastic before or during melting. Oils, greases and sprays applied to an assembled part belong to tribology and are fenced off below the contextual border.

The sections that follow separate internal from external action, explain the polarity and chain-length mechanism behind both, work through the 5 classes, give the phr package for each rigid PVC process with a worked pressure-pipe example, cover over-lubrication and under-lubrication, match a lubricant to each polymer, set out a 6-step selection route, name the test methods, map the EU and US food-contact positions, name the producers and close with the complete list of 16 substance pages. The table below sets the 5 classes side by side before the mechanism explains them.

Melting ranges are supplier grade data (Baerlocher, Struktol); pure-substance melting points from PubChem are given on each substance page. Action labels follow Baerlocher's classification; see the section on why that label is incomplete.

What Is a Lubricant in Plastics Processing?#

A processing lubricant is an additive compounded into a plastic to lower friction during melt processing, either inside the melt, where it reduces viscosity and frictional heat, or at the interface between the melt and the hot metal of the screw, die, calender roll or mold. The additive acts in exactly two places, and the place decides its name: between polymer chains and primary particles it is an internal lubricant, and between the melt and the metal wall it is an external lubricant. Products that do both are called combined lubricants. The whole package is small, between 0.1 and 3 wt% of the finished plastic, which is why a change of 0.1 phr is a formulation decision rather than a rounding error.

Where does that leave the other products called lubricants? Machine oils and greases lubricate the equipment and never enter the compound, and specialty greases and sprays lubricate finished plastic parts such as gears and hinges. Neither is a plastics additive, and neither is covered here.

Why do plastics need processing lubricants?#

Plastics need processing lubricants because the melt sticks: rigid PVC in particular has a high melt viscosity and a thermal window so narrow that the compound would degrade before it flowed freely and released from the metal. PVC grains do not simply melt. They break down into primary particles that then fuse, and the lubricant package controls how fast that happens. R. J. Krzewki and E. A. Collins showed in the Journal of Macromolecular Science in 1981 that paraffin wax delays the breakdown of PVC resin particles and their fusion, while calcium stearate accelerates or delays fusion depending on temperature and on whether wax is present. That interaction, not the lubricant alone, is what a compounder tunes.

The lubricant package sets 5 properties of a PVC compound:

• Fusion time, which external lubricants prolong.
• Torque and melt viscosity, which internal lubricants reduce.
• Metal release from screw, die and calender roll.
• Surface properties, including clarity, gloss, printability and weldability.
• Plate-out and exudation, both of which follow from over-dosing.

Fusion and stability are not controlled by one additive on its own. The lubricant sits next to the PVC heat stabilizers in every PVC one-pack, and the two are supplied together precisely because a lubricant change moves fusion, and a fusion change moves the heat load the stabilizer has to absorb.

Is a processing lubricant the same as a lubricant for plastic parts?#

No: a processing lubricant is mixed into the plastic before it is melted and does its work inside the extruder, calender or mold, while the greases, oils and sprays sold for plastic gears, hinges and seals are applied to a finished part. The two products share a word and nothing else: one is a formulation ingredient dosed in phr, the other is a maintenance chemical applied by hand or by machine after assembly. A third group sits between them. Additives that stay in the finished part to cut wear in service, such as PTFE, silicone, molybdenum disulfide and graphite, are tribological additives, and they are compounded for service friction rather than for melt friction.

Internal and External Lubricants: What Is the Difference?#

Internal lubricants reduce the frictional forces between the polymer chains and so lower melt viscosity, while external lubricants reduce the adhesion between the melt and the metal surface and so control fusion and metal release. Baerlocher's lubricant brochure of 2017 sets the two effects against each other property by property, and the transition between them is fluid rather than sharp, which is why a third label, combined, exists at all.

Source: Baerlocher lubricant brochure (2017). The matrix describes PVC; the same physics applies to other melt-processed polymers.

What does an internal lubricant do?#

An internal lubricant lowers the friction between the polymer chains themselves, which cuts melt viscosity, torque and frictional heat without delaying fusion or clouding a clear compound. It works because it is compatible with the polymer, so it distributes through the melt instead of migrating to the wall, and because that compatibility comes from a polar group on a moderate chain: hydroxyl, carboxylate and calcium carboxylate groups on C14 to C18 chains act internally.

The internal lubricants used in PVC melt across a narrow band. Glycerol monostearate at about 40 % monoester melts at 56 to 62 °C, hydrogenated castor oil at 84 to 88 °C, fatty alcohols at 52 to 54 °C and fatty alcohol phthalate at 46 to 50 °C, while calcium stearate melts near 160 °C in the Baerlocher grade range and is nevertheless classified as internal. Because internal lubricants do not exude and do not haze, they are the only option in clear rigid PVC, where a non-polar wax would be visible in the finished article.

What does an external lubricant do?#

An external lubricant reduces the adhesion between the melt and hot metal, which gives metal release and prolongs fusion, and it is usually a non-polar hydrocarbon such as paraffin or polyethylene wax. Non-polar chains above C20 and up to about C100 act externally, because they have no affinity for the polymer and concentrate at the interface instead. Peter Greven states the rule from the other direction: a reduction in polarity produces products with external lubricating effects.

The external lubricants of the PVC range melt higher and wider than the internal ones. Paraffin melts at 54 to 56 °C, synthetic paraffin at 100 to 105 °C, polyethylene wax at 102 to 110 °C, fatty acids at 54 to 60 °C, hydroxy fatty acids at 70 to 80 °C, ethylene bis stearamide at 138 to 144 °C and zinc stearate near 120 °C. Every one of those products carries a cost. External lubrication delays fusion, can produce haze in a clear compound, can exude at high dosage, and can worsen printability and weldability. Struktol states on its technical data sheets that paraffin is not recommended for articles that are to be printed.

Combined lubricants, and why the internal/external label is incomplete#

A combined lubricant acts in both places at once, and the classic examples are glycerol esters and complex esters with a calcium soap, which melt between 50 and 135 °C depending on grade. Glycerol ester grades melt at 50 to 54 °C and complex esters with a calcium soap at 125 to 135 °C, so a formulator selects the combined grade whose melting range matches the point in the screw where the effect is wanted.

Elvira B. Rabinovitch, Lacatus and James W. Summers argued in the Journal of Vinyl Technology in 1984 that classifying lubricants as internal or external is "deficient in explaining performance". Working from differential thermal analysis, haze measurement, microscopy, metal-release tests and Brabender fusion data, they concluded that polar lubricants such as calcium stearate wet the metal preferentially and are the real metal lubricants, that non-polar paraffin does not wet metal at all but works by making the calcium stearate layer more fluid, and that lubrication between PVC primary particles follows the same physics as lubrication at the metal wall. The Baerlocher classification survives because it predicts the practical outcome, not because it describes the mechanism.

That distinction explains a result the labels cannot. Calcium stearate is classed as internal and zinc stearate as external, although the two soaps differ mainly in melting point and metal-wetting behaviour rather than in polarity class. The practical balance for each rigid PVC process is worked through on lubricants for PVC compounding, where the internal and external halves of the package are set against fusion time.

How Do Processing Lubricants Work? Polarity, Chain Length and the Metal Interface#

Processing lubricants work in 3 ways: they separate polymer chains and particles inside the melt, they wet the hot metal so the melt slides instead of sticking, and they melt or bloom at a defined temperature so the effect starts where it is needed. Chain length and polarity decide which of the three dominates.

1. Separation inside the melt. A polar head group on a C14 to C18 chain, such as a hydroxyl, a carboxylate or a calcium carboxylate, stays compatible with the polymer and keeps chains and primary particles apart, which lowers inner friction and melt viscosity. Glycerol monostearate is the reference case.
2. Wetting of the hot metal. Polar soaps reach the metal wall and form the layer that actually carries the load, and non-polar paraffin, which does not wet metal, makes that layer more fluid (Rabinovitch, Lacatus and Summers, 1984). Oxidation adds polar groups to polyethylene wax, and those groups anchor the wax to the metal, which is why oxidized PE wax gives the strongest metal release per phr of any wax in the family.
3. Melting or blooming at a set temperature. Zinc stearate melts near 120 °C and therefore spreads evenly as the compound heats (Baerlocher), and it migrates to the part surface to form a release layer (Peter Greven), so the grade's melting range is chosen against the process temperature profile.

Grade data from the Baerlocher product range; individual grades differ. Pure-substance melting points (calcium stearate 179 °C, zinc stearate 130 °C, PubChem) appear on the substance pages.

5 Classes of Processing Lubricants#

The 5 classes of processing lubricants are hydrocarbon waxes, metal soaps, fatty acids and fatty alcohols, ester lubricants and amide lubricants, listed here in the order of the classic rigid PVC package. Silicones and fluoropolymers appear in some supplier catalogues as a sixth group, but their function in plastics is mold release and die-wall coating, so this reference covers them under release agents and processing aids rather than as a lubricant class.

1. Hydrocarbon waxes: paraffin, PE wax, oxidized PE wax and Fischer-Tropsch wax#

Hydrocarbon wax lubricants are non-polar alkane chains, from paraffin at about 200 to 1,000 g/mol up to polyethylene wax at around 10,000 g/mol, and they act externally by keeping the melt off the metal. Molecular weight is the master variable in the class: it sets the melting range, the hardness and the tendency to deposit at the die.

Paraffin wax carries CAS 8002-74-2 and EC 232-315-6, melts at 54 to 56 °C in the Baerlocher L-KM grade, has a dropping point of 67 to 72 °C in the Struktol PE(H)-165 grade, and holds 100 active REACH registrations for EC 232-315-6 (ECHA CHEM, 22 September 2026); Struktol states that it is not recommended for articles that are to be printed. Polyethylene wax, CAS 9002-88-4, has a broad molecular weight distribution with an average up to 10,000 g/mol and melts at 90 to 105 °C in the Struktol PE(H)-100 grade; it is used at 1 to 4 % of the compound in elastomers and, as a polymer, is exempt from REACH registration. Oxidised polyethylene wax, CAS 68441-17-8, reaches a dropping point of 131 °C in the PE(O)-300 grade and 99 to 108 °C in PE(O)-600, and it works in rigid PVC at only 0.07 to 0.3 phr, which makes it the strongest metal-release wax per phr in the family.

Fischer-Tropsch wax is the synthetic member of the class, mainly produced by Sasol, melting at 100 to 105 °C in the Baerolub L-KO grade, with a narrow distribution that reached Mn 776 and Mw 786 Da in one experimental grade; its chemical identifiers and REACH status are not established in our sources, so no CAS number is published for it here. Mhlabeni, Jamiru and Mhike reported in 2024 that lower-molecular-weight waxes tend to worsen die drool, which is the practical limit on the light grades. Montan wax is a hydrocarbon wax only in name: its plastics grades are montanic acid esters, so it is treated with the esters below.

2. Metal soaps (metallic stearates)#

Metal soaps are the calcium, zinc and magnesium salts of stearic acid, and they are the only lubricant class that is also a co-stabilizer, an acid scavenger and an internal release agent.

Calcium stearate carries CAS 1592-23-0 and EC 216-472-8, a molecular weight of 607.0 g/mol and a calcium content of 6.3 to 7.9 % depending on grade. Baerlocher classes it as internal, and it runs at 0.4 to 1.5 phr in rigid PVC pipe. Zinc stearate, CAS 557-05-1 and 632.3 g/mol, melts near 120 °C in the Baerlocher range and at 130 °C as a pure substance (PubChem), is classed as external, runs at about 0.5 % in most plastics according to Struktol, and is the preferred internal release agent in sheet and bulk moulding compound because its lower melting point spreads it evenly (Peter Greven). Magnesium stearate, CAS 557-04-0 and 591.2 g/mol, serves as a lubricant and dusting agent in ABS at 0.3 to 3 parts. Metal soaps are made by 4 routes, precipitation, direct conversion, the melt process and the continuous COAD process, and for polypropylene fibre and film the key specification is the filter index rather than the melting point; a calcium-zinc preblend melts at about 100 °C against 120 to 130 °C for the single soaps (Peter Greven LIGASTAB CZ 30).

The same soaps work as acid scavengers in polyolefins at 0.05 to 0.20 %, where they neutralise the acidic residues left by the polymerisation catalyst rather than lubricating anything. That second job explains why calcium and zinc stearate appear in polyethylene and polypropylene formulations that have no lubrication problem at all.

3. Fatty acids and fatty alcohols#

Fatty acid lubricants are C18 acids, above all stearic acid and 12-hydroxystearic acid, which act externally in PVC through a polar acid head on a long non-polar chain. Stearic acid carries CAS 57-11-4 and a molecular weight of 284.5 g/mol, melts at 69.3 °C as a pure substance (PubChem), and reaches 54 to 64 °C in commercial lubricant grades (Baerlocher FTA at 54 to 60 °C, Peter Greven LIGALUB SH at 55 to 64 °C). A rigid PVC dosage of 0.1 to 0.8 phr circulates for stearic acid, but it is a supplier figure that our sources have not confirmed against a manufacturer data sheet.

Stearic acid matters beyond its own lubricating action, because it is the raw material of the metal soaps, the esters and the amides, and it is the surface coating of calcium carbonate filler at about 1.1 % on filler weight (Radebe et al., 2022). 12-Hydroxystearic acid, CAS 106-14-9 and 300.5 g/mol, melts at 70 to 80 °C, acts as an external lubricant in PVC and is the precursor of calcium 12-hydroxystearate. Fatty alcohols complete the class from the other side: they melt at 52 to 54 °C and act internally, because the hydroxyl group keeps them compatible with the polymer.

4. Ester lubricants: glycerol, glycol, polyol, complex and montan esters#

Ester lubricants are fatty acids esterified with glycerol, glycols, polyols or montanic alcohols, and their polarity, which falls as the ester gets larger and less polar, decides whether they act internally, externally or in both places. The class covers the widest melting range of the five, from 46 °C for a fatty alcohol phthalate to 135 °C for a complex ester with a calcium soap, and its highest-volume member in PVC is glycerol monostearate.

Four esters carry most of the volume in plastics. Glycerol monostearate is the standard internal lubricant for clear rigid PVC and doubles as an antistat in polyolefins, and the 40 to 45 % monoester grade melts at 58 to 60 °C and runs at 0.5 to 1.5 phr in rigid PVC, 0.5 to 1.0 phr in flexible PVC, 0.15 % in LDPE, 0.3 % in HDPE and 0.05 to 0.5 % in PP (Struktol TR 151-40). Ethylene glycol distearate, CAS 627-83-8 and 595.0 g/mol, has a dropping point of 63 to 73 °C and runs at 0.5 to 1.5 phr in rigid PVC for window, siding and profile. Pentaerythritol tetrastearate, CAS 115-83-3 and 1202.0 g/mol, is the internal mold release for polycarbonate at up to 0.5 wt% under 21 CFR 177.1580 and a processing aid for PET and PBT. Stearyl stearate, CAS 2778-96-3 and 537.0 g/mol, is a wax ester whose lower polarity gives a more external effect (Peter Greven).

Montan wax belongs here, not with the hydrocarbon waxes. It carries CAS 8002-53-7, is a lignite extract of 62 to 68 % long-chain esters, 22 to 26 % acids and 7 to 15 % alcohols and hydrocarbons, and melts at 82 to 95 °C in the crude form, while the refined montanic acid esters used in food-contact PVC are specified at a dropping point of 76 to 105 °C in 21 CFR 178.3770.

5. Amide lubricants: EBS and other bis-amides#

Amide lubricants are fatty acid amides, above all the bis-amide EBS, which melts at 135 to 146 °C and works as a lubricant, a dispersant and a release agent at the same time. N,N'-ethylenebis(stearamide) carries CAS 110-30-5 and a molecular weight of 593.0 g/mol, melts at 135 to 146 °C as a pure substance (PubChem) and at 138 to 144 °C in the Baerlocher grade range, and acts internally and externally in ABS, PS, PVC and polyolefins. It is also the pigment and filler dispersant of choice in colour concentrates, and amide and metal-soap blends built on it run at 0.5 to 2.0 % in ABS, PVC and PS (Struktol TR 251). EBS is listed as FCM 250 with no specific SML under Regulation (EU) No 10/2011, is cleared under 21 CFR 178.3860, and holds 9 active REACH registrations (ECHA CHEM, 22 September 2026).

Oleamide is the other amide met in compounding, used at about 0.05 % in film and above 0.5 % for mold release (Struktol TR 121); it is not listed in 21 CFR 178.3860. The primary amides erucamide, oleamide and stearamide are dosed to migrate and are therefore treated on this site as slip agents.

How Much Lubricant Does a Compound Need? Dosage in phr#

Processing lubricants are dosed at 0.1 to 3 wt% of the finished plastic, and in rigid PVC the package is written in phr: typically 0.6 to 1.5 phr of paraffin, 0.6 to 1.5 phr of calcium stearate and 0.1 to 0.2 phr of oxidized PE wax for pipe. Filled compounds break that ceiling, because wood flour and high calcium carbonate loadings raise friction faster than they raise volume. The table below gives the published package for each rigid PVC process and for the three filled systems in our sources.

Packages are Struktol technical data sheet recommendations, and the pressure-pipe range is PPI TR-2-2023. Struktol notes on several sheets: reduce calcium stearate as much as possible for improved flow.

Those figures are all in parts per hundred resin, and the conversion to weight percent changes every one of them; the unit itself, its conversion to wt%, ppm and let-down ratio, is set out on PHR (parts per hundred resin).

Reading a package in the wrong unit is the most common arithmetic error in lubricant troubleshooting, because 1.5 phr and 1.5 wt% differ by the whole filler and plasticizer load.

Dosage also depends on how the additive arrives. Wax and stearate carriers are part of every filler masterbatch, where the lubricant is doing double duty as a dispersion aid for the filler and as a viscosity control for the concentrate, so the level quoted on the masterbatch is not the level reaching the finished part.

Rigid PVC lubricant packages by process#

Opaque rigid PVC runs on a paraffin plus calcium stearate package with a trace of oxidized PE wax, while clear compounds drop the paraffin and use glycerol and complex esters instead, because non-polar waxes can cause haze. Pipe and profile differ only in balance: pipe tolerates the wider 0.6 to 1.5 phr window on both the internal and the external side, while profile tightens both to 0.8 to 1.2 phr because a window profile has to weld and to hold a matched surface over long production runs. Calendering and injection molding replace the paraffin entirely with a hydroxyl glycerol ester at 0.7 to 1.5 phr plus a complex ester, and keep calcium stearate low, at 0.3 to 0.75 phr in calendering.

Clarity is the dividing line. Clear injection molding uses 0.7 to 1.0 phr of hydroxyl glycerol ester with 0.3 to 0.6 phr of complex ester and no wax at all, because internal lubricants keep transparency and do not exude, while an external wax at the same level would show. Filled compounds move in the opposite direction: wood-filled compounds need 1 to 8 %, as set out on lubricants for wood-plastic composites, because the wood flour multiplies the internal friction that the package has to absorb.

Worked example: lubricant level in a PVC pressure-pipe compound#

In the US pressure-pipe range composition of PPI TR-2-2023, the whole lubricant package is 1.80 phr out of 108.03 phr, which is 1.67 wt% of the compound. The 1.80 phr is the sum of the three example values below, not a figure printed in TR-2.

The conversion behind the last column is a single division: weight percent equals the phr of the ingredient divided by the total phr of the compound, multiplied by 100. Applied to the paraffin, 1.20 divided by 108.03 gives 1.11 wt%, and the same arithmetic scales any recipe; check your own recipe with the PHR to weight percent calculator.

Over-lubrication and under-lubrication: what goes wrong#

Over-lubrication shows up as haze, surface exudation, plate-out on dies and calender rolls, and a compound that never fuses properly; under-lubrication shows up as rising torque, melt fracture and material sticking to hot metal. The two faults look nothing alike on the line, which is why the direction of the error is usually obvious before any measurement.

Over-lubrication produces 4 symptoms:

• Haziness in a compound that should be clear, from an external lubricant that is not compatible with the melt.
• Exudation at the article surface, which follows an external lubricant dosed above its solubility.
• Plate-out on dies, calender rolls and screws, fed by over-lubrication, by an incompatible external lubricant, by metal-soap reaction products and by pigment and filler fines. The deposit itself is covered under plate-out in PVC processing.
• Incomplete fusion and low mechanical strength, because too much external lubricant delays fusion past the residence time available.

Under-lubrication produces 3 symptoms:

• Rising torque and melt temperature, because inner friction is no longer controlled.
• Melt fracture and a rough extrudate surface at the output the line needs.
• Material sticking to hot metal, which ends as burnt degradation streaks in the product.

The fix should start with rebalancing the package rather than adding lubricant, since both faults are balance faults. Fusion lost to an external lubricant is recovered with acrylic processing aids for PVC, which promote fusion and raise melt strength instead of delaying it.

A second effect appears in polyolefins rather than in PVC. Musil and Zatloukal at Tomas Bata University reported in 2013 that metallic stearates in Ziegler-Natta polyolefins can contribute to die deposits, and low-molecular-weight waxes feed die build-up (die drool) in the same way, so a polyolefin compound that drools should be rebalanced toward higher-molecular-weight wax rather than dosed with more of the light grade.

Which Lubricant Suits Each Polymer?#

Each polymer takes a different lubricant because the melt and the metal meet differently: rigid PVC needs a paraffin and calcium stearate package to control fusion, polycarbonate needs pentaerythritol tetrastearate at up to 0.5 wt% for mold release, and polyamide needs montan esters to stop die bearding. The polymer sets the melt temperature, the sensitivity to haze, the food-contact route and the failure mode, and the lubricant follows from those four. Every polymer has a full package under additives by polymer, of which the lubricant is one line.

How Do You Select a Processing Lubricant? 6 Steps#

Select a processing lubricant in 6 steps: name the processing problem, identify the polymer and its clarity requirement, decide whether the effect must be internal or external, match polarity and melting range to the process temperature, check the food-contact status, then set the phr and confirm it on a torque rheometer. The order matters, because a lubricant chosen for the wrong problem cannot be rescued by dosage.

1. Name the processing problem. Rising torque, incomplete fusion, poor metal release, surface defects and plate-out are five faults with five different answers.
2. Identify the polymer and whether the compound is clear or opaque. A clear compound rules out the non-polar waxes, since they can produce haze.
3. Choose the action needed: internal, external or combined. Internal lowers torque without moving fusion, external gives metal release and prolongs fusion, and combined does both.
4. Match polarity and melting range to the process temperature. Polar groups on C14 to C18 chains act internally, non-polar chains above C20 act externally, and the grade should melt below the zone where the effect is wanted.
5. Check the food-contact and REACH status for the end use. A substitution that works technically can still fail the compliance file.
6. Set the phr, then confirm on a torque rheometer and on the line.

Those six steps are the lubricant-specific version of a general procedure, and the general framework is on how to select plastic additives, which applies the same order to every family on this site.

Cost enters only at the end, once the action and the compliance route are fixed. Oxidized PE wax at 0.07 to 0.3 phr and paraffin at 0.6 to 1.5 phr are not comparable on price per kilogram, because they are used an order of magnitude apart; compare cost in use with the additive dosage and cost-in-use calculator instead.

How Is Lubricant Performance Tested?#

Lubricant performance is measured as fusion behaviour on a torque rheometer, as melt viscosity by melt flow rate or capillary rheometry, and as melting behaviour by dropping point. No single test predicts line behaviour, which is why the selection sequence ends on the extruder rather than in the laboratory.

Fusion measurement is also where new lubricant chemistries are proved. Song and colleagues reported in the Journal of Polymer Science in 2023 that a low-molecular-weight PVC terpolymer lubricant at 1.5 phr can extend fusion time by 26 %, lower the glass transition temperature by 4.0 °C and raise tensile strength from 54 to 59 MPa with elongation rising from 10 % to 30 %, which shows that a lubricant change moves mechanical properties and not only processing behaviour.

How Are Processing Lubricants Regulated?#

Processing lubricants are regulated mainly as food-contact additives, because the metal soaps, waxes, fatty acids, esters and amides used in plastics carry no harmonised hazard classification and none of them is on the REACH Candidate List (checked 22 September 2026). The restrictions that touch this family come from the silicone and fluoropolymer chemistries at its edge, not from the classic lubricants themselves. Every instrument named below is summarised in plastic additive regulations, which maps the same rules across all 43 families.

Food contact in the EU: FCM numbers and SMLs under Regulation (EU) No 10/2011#

In the EU a processing lubricant may be used in food-contact plastics only if it appears on the Union list of Regulation (EU) No 10/2011, and most lubricants sit there as listed additives with no specific migration limit, so the generic limit of 60 mg/kg and the overall migration limit of 10 mg/dm2 apply. Those two numbers carry the whole family in practice, because the substance-specific limits are the exception rather than the rule.

Metal soaps are the structural exception, and they carry no FCM number of their own. Calcium, zinc and magnesium stearate are covered as salts of authorised stearic acid, FCM 106, under Article 6(3)(a), and what applies to them is the Annex II metal limit rather than a substance SML: zinc is capped at 5 mg/kg since Regulation (EU) 2020/1245, aluminium at 1 mg/kg, lithium at 0.6 mg/kg and barium at 1 mg/kg, while calcium, magnesium, sodium and potassium carry no metal SML at all. Among the waxes, oxidized PE wax is FCM 811 with an SML of 60 mg/kg, while paraffin under FCM 93 carries the tightest specification in the family: an SML of 0.05 mg/kg, an average molecular weight of at least 350 Da, a viscosity of at least 2.5 cSt at 100 °C, at most 40 % of hydrocarbons below C25, and no use against the fatty-food simulants D1 and D2. The Union list and its restrictions are explained on EU 10/2011.

Food contact in the US: 21 CFR sections and GRAS status#

In the United States the stearates are cleared as generally recognised as safe food substances, calcium stearate under 21 CFR 184.1229, zinc stearate under 182.8994 and magnesium stearate under 184.1440, while the waxes and esters are cleared as indirect additives in Parts 177 and 178. Stearic acid itself is GRAS under 184.1090, and calcium stearate carries a second route as a prior-sanctioned stabilizer under 21 CFR 181.29.

The indirect-additive clearances are narrower and carry conditions. Pentaerythritol tetrastearate is permitted under 177.1580 at up to 0.5 wt% of the finished polycarbonate resin and, in the FDA's wording, for use only as a mold release agent. Refined montan esters are cleared under 178.3770 as lubricants for PVC food-contact articles at a dropping point of 76 to 105 °C, oxidized polyethylene under 177.1620 with a number-average molecular weight of at least 1,200, petroleum and synthetic petroleum waxes under 178.3710 and 178.3720, and EBS under 178.3860. Oleamide is not listed in 178.3860, so its use in a food-contact article needs a different route. The 21 CFR sections are mapped on FDA food contact rules, section by section and substance by substance.

Silicone and fluoropolymer lubricants: D4/D5/D6 and PFAS rules#

Two lubricant chemistries carry restrictions that the classic waxes and soaps do not: silicones, because of their cyclosiloxane residues, and fluoropolymer processing aids, because they are polymeric PFAS.

Polydimethylsiloxane is used as an external release agent and as a masterbatch slip additive, and Regulation (EU) No 10/2011 covers it as FCM 575, for grades with a molecular weight above 6,800 Da and a viscosity of at least 100 cSt at 25 °C. Its cyclosiloxane residues D4, D5 and D6 are on the REACH Candidate List and are restricted by Annex XVII entry 70 as amended by Regulation (EU) 2024/1328: at or above 0.1 % by weight in mixtures they may not be placed on the market after 6 June 2026, with later dates of 6 June 2027 for leave-on cosmetics and 6 June 2031 for medical devices and medicinal products. Entry 70 sits with the other REACH Annex XVII restrictions that reach into plastics formulation.

Fluoropolymer processing aids fall under the packaging limits of Regulation (EU) 2025/40, which applies from 12 August 2026 and sets 25 ppb for any targeted PFAS, 250 ppb for the sum and 50 ppm for total PFAS including polymeric PFAS, while the EU universal PFAS restriction remains pending. The alternatives are compared on PFAS-free processing aids.

Who Makes Processing Lubricants? Market and Suppliers#

Lubricants are about 2 % of global plastic additive consumption by weight, and the main producers are the metal-soap and wax specialists: Baerlocher, Peter Greven, Struktol, Clariant, Valtris, Fine Organics and Sasol. No market-size or price figure specific to the plastics lubricant segment is established in our sources, so this page reports the consumption share and links the two price guides rather than quoting a segment value.

Company profiles sit in the directory of plastic additive manufacturers and suppliers, and the family splits cleanly in two at the sourcing stage: the grade-by-grade comparison of calcium and zinc stearate manufacturers sits with the soaps, and wax producers are listed under PE wax and polymer wax manufacturers. Buyers usually run those two tenders separately, because the soap and the wax come from different plants even inside one supplier group.

India is the third centre of the family after Germany and the United States, because the amide, ester and fatty-acid derivatives are oleochemical products; Indian oleochemical producers are listed under plastic additive manufacturers and suppliers in India. Prices move with feedstock rather than with the additive market, so current ranges are tracked on PE wax price and on calcium and zinc stearate prices rather than published here.

Complete List of Processing Lubricant Substances (16 Pages)#

The complete list below gives all 16 processing lubricant substances in our substance directory, with CAS number, class, lubricating action and key food-contact status. Rows follow the class order used throughout this page, and then publication order inside each class.

Glycerol monostearate is filed under antistatic agents and oleamide, erucamide and stearamide under slip agents, although all four are also used as lubricants. Row 16 is listed in the topical map under lubricants but belongs to the processing-aid family.

Each row is a full substance record with identity, dosage, regulatory status and suppliers, and all 435 substance pages sit in the plastic additives database.

How Do Processing Lubricants Differ from Slip Agents, Release Agents and Processing Aids?#

The difference is where and when the additive acts: a processing lubricant works inside the machine during melting, a slip agent works on the finished film, a release agent works at the mold surface and a polymer processing aid works on the die wall. Purpose separates the 4 families, but chemistry does not, because several substances belong to more than one of them. Calcium stearate, zinc stearate, EBS, glycerol monostearate and oleamide all appear under at least two family headings on this site, filed each time by the job they are doing in that formulation rather than by their structure.

Lubricant or slip agent?#

A slip agent is a lubricant that has been chosen to migrate: erucamide and oleamide bloom to the film surface at 500 to 1,200 ppm and lower its coefficient of friction, while a processing lubricant is meant to work in the melt and stay there. Oleamide shows both behaviours at different levels, at about 0.05 % in film and above 0.5 % for mold release (Struktol TR 121), so the dosage decides the family. Slip performance is measured on the finished film to ASTM D1894 rather than in the melt, and the migrating amides are covered as slip additives for plastic film. EBS is not one of them: it is a lubricant and dispersant, and it does not act as a film slip agent.

Lubricant or mold release agent?#

An internal mold release agent is a lubricant dosed so that it blooms to the part surface, such as pentaerythritol tetrastearate in polycarbonate at up to 0.5 wt%, whereas an external release agent is sprayed on the mold and never enters the plastic. Zinc and calcium stearate fill the internal role in sheet and bulk moulding compound, and calcium stearate at 1 wt% does the same in PLA. The FDA wording for PETS makes the distinction legally explicit, clearing it for use only as a mold release agent. Internal and external types are compared on mold release agents, where the external products are treated as process chemicals rather than as additives.

Lubricant or polymer processing aid?#

A polymer processing aid is not a lubricant: the fluoropolymer and PFAS-free grades used in polyolefin film coat the die wall to remove sharkskin, and the acrylic grades used in rigid PVC promote fusion rather than delay it. The polyolefin type is dosed in parts per million and works by inducing wall slip, which raises the critical output at which melt fracture appears. The acrylic type does the opposite of an external lubricant, which is why the two are balanced against each other in a rigid PVC recipe: the lubricant delays fusion for metal release, and the processing aid buys the fusion back. The die-wall mechanism is explained on polymer processing aids.

Is calcium stearate a lubricant, an acid scavenger or a stabilizer?#

Calcium stearate is all three at once: in PVC it lubricates and supports the calcium-zinc stabilizer system, in polyolefins it neutralises acidic catalyst residues at 0.05 to 0.20 %, and in SMC, BMC and PLA it acts as an internal mold release. It works as a pigment wetting agent in colour concentrates as well, and in a Peter Greven test 500 ppm kept a steel plate from corroding. The function follows the polymer and the level, not the substance, which is why the same CAS number appears in four different additive families on this site.

Are processing lubricants hazardous or restricted?#

Processing lubricants are the least restricted additive family on this site: none of the 16 substances in this directory is on the REACH Candidate List (checked 22 September 2026), and calcium stearate carries no classification in 85.5 % of its 3,808 notifications to the ECHA classification and labelling inventory. Zinc stearate is the one worth reading carefully: 61.3 % of its 2,108 notifications report no classification, while minority notifications give H400 (30.9 %), H413 (22.7 %) and H335 (28.3 %), which matters for the labelling of a masterbatch even where it does not change the additive's use. Pentaerythritol tetrastearate is not classified in all 416 of its notifications. The exception to the pattern is the cyclosiloxane residues D4, D5 and D6 in silicones, and the families that do carry restrictions are listed on toxic plastic additives.

How do lubricants affect plastics recycling?#

Lubricants make heavily filled and recycled compounds processable again: 3 wt% of wax with 1.0 wt% of zinc stearate returned a 60 wt% calcium carbonate masterbatch in LLDPE to just above the melt viscosity of the neat polymer in work by Radebe and colleagues at the University of Pretoria in 2022, where the filled compound had started at 3 times the neat viscosity. The same lever can restore flow in recyclate compounds, whose viscosity rises with contamination and with repeated heat history. Adding lubricant is not automatically the answer, because low-molecular-weight waxes and metallic stearates in Ziegler-Natta polyolefins can contribute to die drool, so a recyclate compound needs the package rebalanced rather than simply increased. The wider recyclability picture is on design for recycling.

What about lubricants for finished plastic parts?#

Greases, oils and sprays for assembled plastic parts are outside the scope of this reference, which covers additives compounded into the plastic. The additives that do stay in a finished part to cut wear in service, such as PTFE, silicone, molybdenum disulfide and graphite, are compounded into gears, bearings and bushings during moulding and are treated on this site as tribological additives rather than as processing lubricants.