Calcium Stearate: Properties, Uses in Plastics and Regulatory Status

Calcium stearate (calcium distearate, CAS 1592-23-0) is a metal soap used in plastics as a lubricant in PVC, as an acid scavenger in polyolefins and as an internal mold release agent, which makes it one of the few additives that appear in three different additive families at once. Because the same powder does three jobs, the question that decides a formulation is not what calcium stearate is, but how much of it a given compound needs. Its molecular formula is C36H70CaO4 and its molecular weight 607.0 g/mol.

A rigid PVC pipe compound carries 0.6 to 1.5 phr of it and a polypropylene grade only 0.05 to 0.20 %, on a settled regulatory base: registered under REACH, absent from the Candidate List of Substances of Very High Concern as of 22 September 2026, and generally recognised as safe in the United States under 21 CFR 184.1229. Calcium stearate is one of 437 substance profiles in our directory of plastic additives, each with the same identity, dosage and regulatory fields.

Five things organise everything below: one calcium ion carrying two C18 chains explains all 3 mechanisms, the melting point splits into 179 °C (354.2 °F) pure and 140 to 165 °C (284 to 329 °F) commercial, the dosage runs from 0.3 phr in calendering to 1.5 phr in pipe and down to 500 ppm in polypropylene, the EU reaches the substance through stearic acid, and zinc stearate, magnesium stearate, hydrotalcite and zinc oxide each replace only one of its jobs.

The identity table below collects the values that a specification, a customs declaration and a food-contact declaration ask for.

What Is Calcium Stearate?#

Calcium stearate is the calcium salt of stearic acid (octadecanoic acid): one calcium ion holds two C18 fatty-acid chains, which gives the molecule a polar head and two long non-polar tails. That architecture explains every job the powder does. The polar carboxylate head is attracted to metal surfaces, to pigment surfaces and to the polar sites on a PVC chain, while the two C18 tails are compatible with the hydrocarbon part of a polymer melt. Which substances does the name calcium stearate actually cover? Industrial calcium stearate is built from a commercial C16 to C18 fatty-acid cut rather than from pure octadecanoic acid, so a drum of it is a mixture with a specification, not a single pure compound, and the trade counts it among the processing lubricants for plastics rather than among the stabilizers.

As a metal soap, calcium stearate belongs to the family of processing lubricants for plastics, where the hub compares the 4 lubricant classes used in polymer compounding: the metallic soaps, the hydrocarbon waxes, the fatty-acid esters and the fatty amides. Within that family the metal soaps are the polar members, which is why they carry functions no wax has. Our data set records 5 functions for calcium stearate: lubricant in PVC, acid scavenger and catalyst neutralizer in polyolefins, internal mold release agent in SMC, BMC and PLA, co-stabilizer in calcium-zinc PVC systems, and pigment wetting agent in colour concentrates.

What is another name for calcium stearate?#

Calcium stearate is also called calcium distearate, calcium octadecanoate and, on chemical inventories, octadecanoic acid calcium salt; compounders usually call the whole group metal soaps or metallic stearates. The abbreviation on a formulation sheet is CaSt, and the trade names in commercial use are CEASIT (Baerlocher), LIGASTAR CA (Peter Greven) and STRUKTOL Calcium Stearate. All of these names carry the same CAS number, 1592-23-0.

Is calcium stearate the same as stearic acid?#

No: stearic acid (CAS 57-11-4, 284.5 g/mol) is the free fatty acid and the raw material, while calcium stearate (CAS 1592-23-0, 607.0 g/mol) is its calcium salt, and the salt melts more than 100 °C (180 °F) higher. Stearic acid melts at 69.3 °C (156.7 °F); calcium distearate melts at 179 °C (354.2 °F) as a pure substance. Stearic acid is itself an external lubricant in PVC and the raw material from which every metal soap is made, so the two appear in the same recipes without being interchangeable. The practical consequence is that residual stearic acid in a calcium stearate powder is measured as free fatty acid and capped by specification, because it shifts the softening behaviour of the grade.

What is calcium stearate made from?#

Calcium stearate is made from stearic acid (usually a commercial C16 to C18 fatty-acid cut) and a calcium source, by 4 industrial routes that Peter Greven distinguishes: precipitation, direct conversion, the melt process and the continuous COAD process. The route sets particle shape, bulk density, dust behaviour and dissolution rate, and therefore how the same nominal substance behaves in a dry blend or in a fibre line. The 4 routes are described below.

• Precipitation (the indirect, two-step route) gives a very fine powder with a high surface area, a low bulk density and a higher salt content.
• Direct conversion adds the metal base powder below the melting point of the soap and runs at a pH above 7.
• The melt process runs above the melting point of the soap and gives a dust-free clear melt.
• The COAD continuous process is dust-free and neutral in pH, and it produces layered particles that dissolve faster and give a low filter index for polypropylene fibre.

The feedstock origin of the fatty-acid cut, whether vegetable, animal or synthetic, is not recorded in our verified data set, so this page states the chemistry and not the raw-material source.

Why grades differ: calcium content, ash, free fatty acid and filter index#

Two calcium stearate powders with the same CAS number are not interchangeable: grades differ in calcium content (about 6.3 to 7.9 %, Peter Greven), ash (9.2 to 12.0 %) and free fatty acid (maximum 3.0 %, Struktol). Calcium content measures how completely the fatty acid was converted into the salt. Ash reports the inorganic residue after combustion. Free fatty acid reports the unreacted stearic acid left in the powder, and it is the specification that most directly shifts the softening range of a grade. The filter index, reported in bar per kilogram, measures how much a powder raises screen pressure in a filtration test, and it is a key specification for polypropylene fibre and film, where the COAD route is used precisely because it gives a low value.

These 4 numbers, and not the CAS number, decide how a grade runs. Grade specifications differ by producer, so read the certificate of analysis before treating two powders as equivalent.

How Does Calcium Stearate Work in a Polymer?#

Calcium stearate works in 3 different ways in a polymer: it wets hot metal surfaces as a lubricant, it neutralizes acidic catalyst residues as an acid scavenger, and it migrates to the part surface as an internal mold release agent. Which of the 3 dominates depends on the polymer and on the dose. In rigid PVC at 0.3 to 1.5 phr the lubricant function is the reason it is there; in polypropylene at 0.05 to 0.20 % the acid-scavenging function is; in a sheet moulding compound or in injection-moulded PLA the release function is. The 3 mechanisms are set out under the headings below.

Lubrication: why calcium stearate wets hot metal#

Calcium stearate lubricates by wetting hot metal: Rabinovitch and colleagues showed in 1984 (Journal of Vinyl Technology) that the polar carboxylate head adsorbs on the steel surface, so the polar soap, not the non-polar paraffin, is the true metal lubricant. Paraffin does not wet metal at all. Its contribution, in the same 1984 work, is to make the adsorbed calcium stearate layer more fluid, which is why the two additives function as a pair in a pipe recipe rather than as alternatives. A compounder who removes the paraffin does not remove a redundant wax; the soap layer that remains is stiffer than the one the recipe was balanced around.

The labels used in the trade run against this mechanism, which is the single most common source of selection error. Baerlocher classes calcium stearate, melting at about 160 °C (320 °F), as an internal lubricant, and zinc stearate, melting at about 120 °C (248 °F), as an external one, where an internal lubricant reduces friction between PVC chains and lowers melt viscosity, and an external lubricant reduces adhesion between PVC and metal and prolongs fusion. Calcium stearate is therefore filed as internal although it is the soap that wets the steel. Selecting by the internal and external labels alone is risky, which is why the balance is explained on lubricants for PVC compounding, where the melting point of each component is set beside its label.

Acid scavenging: how it neutralizes catalyst residues#

In polyolefins calcium stearate is an acid scavenger: it neutralizes the hydrogen chloride released by Ziegler-Natta catalyst residues, which otherwise corrodes tooling, discolours the polymer and hydrolyses phosphite antioxidants. The residues in question are the titanium, aluminium and magnesium chlorides left in the resin after polymerization. Water reaching those chlorides liberates hydrogen chloride, and the acid then attacks 3 things at once: the steel of the extruder and the die, the colour of the polymer, and the stabilizer package, where it antagonises the phenolic antioxidant and hydrolyses the phosphite.

Calcium stearate is one of 4 classes of acid scavengers and catalyst neutralizers used in polymers, and it is the oldest of them. The neutralization reaction converts the soap into calcium chloride and frees the stearic acid, which is the mechanism and also the limitation: calcium chloride is hygroscopic, so the captured chloride stays in the compound as a water-attracting salt rather than being locked away.

Mold release: why it migrates to the part surface#

As an internal release agent, calcium stearate is dosed into the compound and migrates to the surface of the part during moulding, where it forms the layer that lets the part leave the tool. Additives dosed into the compound rather than sprayed on the tool are internal mold release agents, and the 4 chemistries used for that job are waxes, fatty esters, silicones and metallic soaps. Calcium stearate belongs to the fourth group.

Particle morphology decides how well a given grade releases. Peter Greven reports that precipitated grades release particularly well because of their fineness, and Baerlocher sells CEASIT SW 1725 for sheet and bulk moulding compounds on that basis. The migration that creates the release layer is the same movement that, in a metallized film, deposits soap where an evaporated metal layer has to bond, which is why the release mechanism and the metallization problem described further below are two readings of one physical effect.

What Are the Physical and Chemical Properties of Calcium Stearate?#

Calcium stearate is a white powder with a molecular weight of 607.0 g/mol, a density of 1.12 g/cm3 and a water solubility of only 0.004 g per 100 mL at 15 °C (59 °F). PubChem describes its appearance as a granular fatty powder. The table below lists the pure-substance values beside the commercial grade specifications, because the two sets of numbers answer different questions.

The melting point is the most-queried property of calcium stearate and the one most often quoted wrongly, because two correct answers exist. PubChem gives 179 °C (354.2 °F) for the pure distearate, while commercial grades soften between 140 and 165 °C (284 and 329 °F) because they are fatty-acid cuts rather than pure distearate and carry free fatty acid and moisture. Published values of 147 to 149 °C circulate in secondary sources; they match neither PubChem nor the supplier data sheets, so check which one a specification refers to. The calcium content figure carries a similar caution: our data set records about 6.3 to 7.9 % for the Peter Greven grades while the processing dossier prints 6.3 to 7.3 % for the same grades, so the range is given as grade-dependent and the certificate of analysis decides.

Which Polymers Use Calcium Stearate, and at What Dosage?#

Calcium stearate is dosed in parts per hundred resin in PVC and in parts per million in polyolefins: a rigid PVC pipe compound carries 0.6 to 1.5 phr, while a polypropylene grade needs only 0.05 to 0.20 % as an acid scavenger. That factor of roughly 10 between the two families is the single most useful number on this page, because it separates a lubricant dose from a neutralizer dose. The full set of documented levels, with the rest of the lubricant package beside each one, is listed in the table below.

How do phr values convert to weight percent? A phr figure is a part per hundred parts of resin, so the weight percent of any ingredient equals its phr value divided by the total phr of the recipe, multiplied by 100. PVC recipes give calcium stearate in PHR (parts per hundred resin), which converts to weight percent only once the full formulation total is known.

The worked pressure-pipe compound in PPI TR-2 shows the arithmetic. It totals 108.03 phr, of which calcium stearate is 0.45 phr, so the soap is 0.42 wt% of the finished compound while the PVC resin itself is 92.57 wt%. The conversion for a full recipe runs in the PHR to weight percent calculator, which takes the whole ingredient list rather than a single line.

Rigid PVC: pipe, profile, injection moulding and calendering#

A rigid PVC pipe compound carries 0.6 to 1.5 phr of calcium stearate, paired with the same amount of paraffin wax and 0.1 to 0.2 phr of an oxidized polyethylene wax (Struktol PE(H)-165 data sheet). The pipe package pairs calcium stearate with paraffin wax at the same level, which is the balance the 1984 metal-wetting work predicts: the polar soap holds the steel, the non-polar wax keeps that layer mobile. A profile compound narrows both figures to 0.8 to 1.2 phr, because a profile die is longer and the tolerance for over-lubrication is smaller.

Injection moulding and calendering use less. Struktol gives 0.3 to 1.0 phr for opaque rigid PVC injection moulding alongside a hydroxyl glycerol ester and a complex ester, and 0.3 to 0.75 phr for opaque calendering, where the ester lubricants carry more of the load at 0.7 to 1.5 phr and 0.5 to 0.75 phr respectively.

In the United States, calcium stearate is a prequalified ingredient for PVC pipe under Plastics Pipe Institute TR-2 (2023), whose range composition allows 0.4 to 1.5 phr and whose Part A.2 specification names a melting point of 145 to 165 °C (293 to 329 °F) with substitution permitted at 1.5 phr or less. Struktol adds one caution to all of these figures: reduce calcium stearate as much as possible for improved flow. The third component, oxidized polyethylene wax, is dosed at 0.1 to 0.2 phr in both the pipe and the profile recipe.

Polyolefins (PP and PE): acid scavenger levels#

In polyolefins the level is far lower than in PVC: Peter Greven gives 0.05 to 0.20 % for metal soaps as acid scavengers, and reports that 500 ppm of calcium stearate kept a steel plate from corroding in a polypropylene test. One widely quoted upper figure of up to 1000 ppm circulates in encyclopedia sources; the Peter Greven range is the primary number here. Expressed in the same unit, 0.05 to 0.20 % is 500 to 2000 ppm, so the corrosion test sits at the bottom of the documented window.

A second measurable effect of the same dose is stabilizer survival. Espelage and colleagues (Polymers, 2025) found that more Irgafos 168 was retained after compounding when calcium stearate was present, and they call the effect particularly relevant immediately after polymerization, when the catalyst residues are still fully active and the acid load on the phosphite is highest. The three-way comparison with hydrotalcite and zinc oxide sits on acid scavengers for polyolefins, which sets the soap route against the two mineral routes.

PLA, unsaturated polyester (SMC/BMC), polyamide and SAN#

Outside PVC and the polyolefins, calcium stearate appears as a release agent: Tábi and Pölöskei (2021) used 1 wt% in injection-moulded PLA, where it addressed stuck and broken parts. That 1 wt% figure is the only quantified release dose for calcium stearate in our verified data set, and it belongs to PLA alone. The rest of the PLA package is on additives for PLA, where the nucleating agents, plasticizers and chain extenders that accompany it are covered.

In unsaturated polyester sheet and bulk moulding compounds the soap performs the same migration to the surface, but no dosage is recorded for calcium stearate in our data set, and zinc stearate is the preferred soap there because of its lower melting point. Baerlocher additionally offers CEASIT grades for polyamide and SAN, again without a published level. Where no number exists, this page names the role and leaves the dosage to the supplier data sheet rather than transferring a figure from a neighbouring polymer.

What Is Calcium Stearate Used For? 6 Uses in Plastics#

Calcium stearate is used for 6 jobs in plastics: lubrication of rigid PVC, neutralization of catalyst residues in polyolefins, the calcium half of calcium-zinc stabilizer systems, internal mold release, pigment wetting in colour concentrates, and low-filter-index grades for polypropylene fibre and film. The 6 uses are ranked below by the volume of calcium stearate each one consumes, and the sections that follow take the first 5 in the same order.

• PVC pipe, profile, siding and fittings, where the soap is part of the lubricant package.
• Catalyst-residue neutralization in polypropylene and polyethylene.
• Calcium-zinc PVC stabilizer systems, where the calcium soap regenerates the zinc soap.
• Internal mold release in SMC, BMC and injection-moulded PLA.
• Pigment wetting in colour concentrates and masterbatch.
• Polypropylene fibre and film, where low-filter-index grades keep screen pressure down.

PVC pipe, profile and fittings#

Rigid PVC pipe is the largest single plastics use: calcium stearate appears in the Plastics Pipe Institute TR-2 range composition at 0.4 to 1.5 phr and in its worked pressure-pipe formulation at 0.45 phr. That worked formulation reads PVC resin 100, heat stabilizer 0.70, paraffin 1.20, polyethylene wax 0.15, calcium carbonate 5.00, titanium dioxide 0.50, pigment 0.03 and calcium stearate 0.45, totalling 108.03 phr. Profile and fitting compounds use the same 3-part lubricant logic at slightly different levels, with the soap between 0.8 and 1.2 phr for profile, and the rigid PVC formulations behind both rest on the same stabilizer and filler lines.

Why does a pipe recipe need both a soap and a wax? The soap holds the metal surface and the wax keeps the layer mobile, so the pair sets both the release from the die and the fusion behaviour of the dry blend. Raising the soap alone raises the risk that Struktol warns about, namely a loss of flow, while raising the wax alone delays fusion. Complete recipes for pipe, profile and sheet sit on rigid PVC formulations.

Pressure pipe adds one more layer of qualification, because the additives for PVC pipe that touch drinking water are approved separately from the compound itself. Drinking-water approvals and the rest of that package are covered under additives for PVC pipe.

Catalyst-residue neutralization in polypropylene and polyethylene#

In polypropylene and polyethylene the job is chemical, not mechanical: calcium stearate neutralizes the acid left by the polymerization catalyst, and Espelage and colleagues (Polymers, 2025) measured more Irgafos 168 surviving compounding when it is present. The acid scavenger is one line of the additives for polypropylene package, sitting beside the phenolic antioxidant, the phosphite, the nucleator and the light stabilizer.

The soap route carries 2 documented limits. The calcium chloride formed on neutralization is hygroscopic, and Kisuma reports that in polypropylene raffia tape this raises water carry-over, while migrating metal soaps can impair the metallization of BOPP film. A 2023 review in Materials separately reports that calcium stearate can act as a pro-oxidant for polypropylene under natural exposure, which is a long-term weathering consideration rather than a processing one. Both limits are reasons formulators move to a mineral scavenger, not reasons the soap fails at its primary job.

Calcium-zinc PVC stabilizer systems#

Calcium stearate is also the calcium half of the lead-free stabilizer system that has replaced lead in Europe: calcium-zinc and calcium-organic systems together account for 83 % of EU PVC stabilizer use (VinylPlus, June 2023). In the calcium-zinc pair the zinc soap substitutes labile chlorine on the PVC chain and forms zinc chloride, and the calcium soap regenerates the zinc soap from it, which is what keeps the aggressive zinc chloride from accumulating. Peter Greven supplies the pair as a preblend, LIGASTAB CZ 30, which melts at about 100 °C (212 °F) against 120 to 130 °C (248 to 266 °F) for the single soaps. The full mechanism of calcium-zinc stabilizers, including the co-stabilizers that control zinc chloride, is on the stabilizer page.

Internal mold release in SMC/BMC and PLA#

In sheet and bulk moulding compounds the release job is shared: zinc stearate is preferred for its lower melting point, while calcium stearate is used where higher thermal stability matters. Precipitated grades release best in both cases because of their fineness. Release systems for SMC and BMC are compared on mold release agents for composites, which sets the internal soaps against the sprayed and semi-permanent systems.

Pigment wetting in colour concentrates and masterbatch#

In colour concentrates calcium stearate wets the pigment surface, which helps the pigment disperse and keeps the filter pressure value down. The same polar head that adsorbs on steel adsorbs on a pigment particle, displacing air and letting the polymer melt reach the surface. Pigment wetting is one of the formulation steps behind color masterbatch. No dosage for calcium stearate in colour concentrates is recorded in our verified data set, so no figure is given here.

How Does Calcium Stearate Perform? Fusion, Flow and Corrosion#

Calcium stearate does not have one fixed effect on PVC fusion: Krzewki and Collins reported in 1981 that it can either accelerate or delay fusion, depending on the processing temperature and on whether a paraffin wax is present. In the same 1981 work, paraffin wax on its own delays resin particle breakdown and fusion, while with wax present in the formulation more calcium stearate enhances fusion. The direction of the effect is therefore a property of the package, not of the soap.

Flow runs the other way from fusion, and this is the trade-off a compounder balances. Struktol advises reducing calcium stearate as much as possible for improved flow in its PE(H)-165 note, so the level that fuses best is not the level that flows best. Order of addition and fusion behaviour are covered under PVC dry blending, where the same soap enters the hot mixer at a defined point in the sequence.

Two further effects are documented, one protective and one unwanted. On the protective side, 500 ppm of calcium stearate kept a steel plate from corroding in a polypropylene test reported by Peter Greven, and Espelage and colleagues (Polymers, 2025) found more phosphite antioxidant retained after compounding in its presence. On the unwanted side, the review of die drool by Mhlabeni, Jamiru and Mhike (Frontiers in Chemical Engineering, 2024) names metallic stearates in Ziegler-Natta polyolefins among the contributors to die lip build-up. The performance table below sets each indicator beside its evidence.

No torque-rheometer values, no fusion times in seconds and no melt-flow figures for calcium stearate are held in our verified data set, so this section names each effect and its direction without attaching a number to it.

How Does Calcium Stearate Interact with Other Additives?#

Calcium stearate is almost never used alone: it is paired with paraffin wax in PVC, with zinc stearate in stabilizer systems, and it changes how the antioxidant and nucleator packages behave in polyolefins. The 4 documented interactions are listed below.

• Paraffin wax fluidizes the adsorbed calcium stearate layer on hot metal, so the two are a pair rather than alternatives (Rabinovitch and colleagues, 1984).
• Zinc stearate forms zinc chloride when it substitutes labile chlorine in PVC, and the calcium soap regenerates the zinc soap from that chloride.
• Phosphite antioxidants survive compounding better in polypropylene when calcium stearate is present, because the soap removes the acid that hydrolyses them: more Irgafos 168 survived compounding when calcium stearate was present (Espelage and colleagues, 2025).
• Benzoate nucleators interact negatively with the soap at commercial levels in polypropylene.

The nucleator interaction is the one that most often surprises a formulator, because both additives are routine at parts-per-million levels and neither is chemically aggressive on its own. Simanke and colleagues (2016) reported a negative interaction between calcium stearate and sodium benzoate at 1000 to 2200 ppm in polypropylene, which is the window in which both are normally dosed. A trial that changes the acid scavenger therefore needs to re-check the nucleation result rather than assume it carries over.

What Is the Regulatory Status of Calcium Stearate?#

Calcium stearate is registered under REACH, is not a Substance of Very High Concern, reaches EU food-contact plastics as a salt of authorised stearic acid rather than through an entry of its own, and is GRAS in the United States under 21 CFR 184.1229 (status 24 September 2026). The matrix below gives each instrument with its date and reference.

Three cells in that matrix read "not recorded in our source library" rather than "not listed", because an absence we have not checked against the primary list is not a negative finding. Registration, evaluation and the Candidate List process are explained on REACH and plastic additives, which sets out what a full Article 10 dossier covers and what it does not.

Is calcium stearate REACH registered, and is it an SVHC?#

Yes, calcium stearate is registered under REACH with 10 active full registration dossiers, and no, it is not a Substance of Very High Concern: it is absent from the Candidate List as of 22 September 2026. Ten active Article 10 dossiers under ECHA CHEM entry 100.014.976 place it among the well-registered additives. Every plastic additive currently on the SVHC Candidate List is tracked on that page; calcium stearate has never been added to it. No tonnage band is stated here, because the registered volume is not held in our verified data set.

Is calcium stearate allowed in food-contact plastics?#

Yes in both jurisdictions, but by different routes: in the EU calcium stearate is not listed on its own but is allowed as a salt of authorised stearic acid (FCM substance 106) under Article 6(3)(a) of Regulation (EU) No 10/2011, and calcium carries no metal limit in Annex II. Stearic acid itself is FCM 106, entered as Ref 24550 as a monomer and Ref 89040 as an additive, and Article 6(3)(a) extends that authorisation to its salts without a separate entry. With no specific migration limit of its own and no Annex II metal limit for calcium, the constraint that applies is the generic overall migration limit of 10 mg/dm2. Article 6(3)(a) and the Annex II metal limits are explained on EU 10/2011.

In the United States calcium stearate is generally recognised as safe under 21 CFR 184.1229 and appears on the prior-sanctioned list in 21 CFR 181.29, where no migrant limit is stated for it.

The practical consequence of the EU route is a calculation difference between the two soaps. Switching from calcium stearate to zinc stearate brings a zinc migration limit of 5 mg/kg into the compliance calculation, added to Annex II by Regulation (EU) 2020/1245, while calcium brings no such limit. How GRAS listings and prior sanctions differ from food-contact notifications is set out in the FDA food contact rules for plastic additives.

Why does 21 CFR 184.1229 print a different CAS number?#

The eCFR text of 21 CFR 184.1229 prints CAS 1529-23-0, which is a transposition typo: the correct CAS number for calcium stearate is 1592-23-0, as PubChem and the ECHA registration both show. The error has propagated into supplier documents and into search results that quote the regulation verbatim. Quote the regulation as printed when citing 21 CFR 184.1229, and use 1592-23-0 in specifications, certificates of analysis and customs paperwork.

Is Calcium Stearate Safe? Health, Safety and Environmental Profile#

Calcium stearate has no harmonised CLP classification, and in the ECHA classification and labelling data aggregated by PubChem, 85.5 % of 3,808 notifications report that it is not classified. A minority of notifiers report 2 hazard statements: H319 for serious eye irritation and H335 for respiratory irritation. Both are consistent with what a fine, low-bulk-density powder does mechanically rather than with a toxicological property of the salt. The 3 status points our data set records are listed below.

• Classification: no harmonised CLP entry; 85.5 % of 3,808 C&L notifications report "not classified", with H319 and H335 notified by a minority.
• REACH: not a Substance of Very High Concern as of 22 September 2026.
• Food and food-contact recognition: GRAS under 21 CFR 184.1229 in the United States, and permitted in EU food-contact plastics as a salt of authorised stearic acid.

The practical reading of that record is that the residual handling concern for calcium stearate is dust, not the hazard profile of the substance, which is why the melt and COAD process routes are sold as dust-free. California Proposition 65, US TSCA and the EU POPs Regulation are not recorded in our source library for this substance, and no toxicological values are stated here, because none are held in our verified data set.

Migration is a separate question from classification, and it is the one a food-contact formulator actually asks. What actually migrates from food-contact plastics is reviewed under chemicals migrating from plastic food packaging, which covers the additive classes measured in real packaging rather than the classification of the raw powder.

What Are the Alternatives to Calcium Stearate?#

The 4 alternatives named in our source library are zinc stearate, magnesium stearate, hydrotalcite and zinc oxide, and the substitution only works job by job: a release agent replacement is not an acid scavenger replacement. The comparison table sets identity, melting point, food-contact route and Annex II metal limit beside the one job each substance takes over.

Reading the table by column rather than by row is what makes the substitution decision. The metal soaps share a food-contact route and differ in melting point; the mineral scavengers share a capture mechanism and differ in metal limit. The class comparison, including the full calcium stearate against zinc stearate verdict, sits on metal stearates.

Calcium stearate vs zinc stearate#

The deciding property is the melting point: calcium stearate melts around 160 °C (320 °F) and zinc stearate around 120 °C (248 °F), which is why zinc spreads earlier and releases better while calcium survives the hotter part of the process. Zinc stearate melts about 40 °C (72 °F) lower, which is why it releases earlier in the moulding cycle and why it is the preferred soap in sheet and bulk moulding compounds. Baerlocher classes the zinc soap as external and the calcium soap as internal on the same melting-point logic.

Two further differences decide food-contact and hazard questions. Zinc stearate carries a zinc migration limit of 5 mg/kg under Annex II of Regulation (EU) No 10/2011, while calcium carries none, and the classification records differ: calcium stearate is not classified in 85.5 % of 3,808 notifications, while zinc stearate is not classified in 61.3 % of 2,108 notifications, with H400 for acute aquatic toxicity notified in 30.9 % of them. The full head-to-head verdict, including the cases where the two soaps are blended rather than substituted, belongs to the class page rather than to this substance record.

Calcium stearate vs hydrotalcite and zinc oxide#

The practical difference is what happens to the chloride after capture: calcium stearate turns into hygroscopic calcium chloride, while hydrotalcite locks the chloride into its interlayer and does not migrate. Hydrotalcite captures chloride irreversibly in its interlayer instead of forming a hygroscopic salt, which removes the water carry-over problem that Kisuma reports for polypropylene raffia tape and the migration that can impair metallization of BOPP film.

Capacity and regulatory footprint follow from the same difference. Kisuma claims about 3 times the effectiveness of conventional acid scavengers for its layered double hydroxide, a supplier figure quoted here without a stated test method, while the EU food-contact position differs by metal rather than by chemistry: hydrotalcite is a listed FCM substance with no specific migration limit but with an aluminium limit of 1 mg/kg in Annex II.

The third route is a metal oxide rather than a soap or a clay. Zinc oxide is the third scavenger route and carries the same 5 mg/kg zinc limit as the zinc soap, and it is listed as FCM 402. Against all 3, calcium stearate keeps 2 advantages that keep it in service at 0.05 to 0.20 %: it carries no metal limit in Annex II, and it lubricates while it scavenges.

Calcium stearate vs magnesium stearate#

Magnesium stearate is the specialist of the three soaps: in plastics it lubricates and releases ABS, SAN and polyamide at 0.3 to 3 parts, while calcium stearate carries the PVC and polyolefin volume. Magnesium stearate is used mainly in ABS, SAN and polyamide at 0.3 to 3 parts, at CAS 557-04-0 and 591.2 g/mol, with a melting point of 88.5 °C (191.3 °F) for the pure substance and 132 °C (269.6 °F) for the technical grade. Magnesium, like calcium, carries no metal limit in Annex II of Regulation (EU) No 10/2011, so the two soaps are equivalent on that point.

No active REACH dossier for magnesium stearate was found in the ECHA CHEM search of 22 September 2026, so no REACH status is stated for it on this page. The consumer-facing magnesium stearate queries about supplements and tablets belong to a different subject area and are not answered here.

Who Manufactures Calcium Stearate? Grades and Suppliers#

Calcium stearate is produced by the metal-soap specialists rather than by the large additive houses: Baerlocher sells it as CEASIT, Peter Greven as LIGASTAR CA and Struktol under its own name. Each of the 3 publishes a different part of the specification, which is why the cross-supplier view below exists at all: Baerlocher documents application grades, Peter Greven documents process routes and metal content, Struktol documents ash and free fatty acid.

Buyers should ask for the calcium content, the ash and free-fatty-acid specification, the filter index for fibre and film grades and the production route, because these, not the CAS number, decide how a grade behaves. A precipitated grade and a COAD grade with identical CAS numbers differ in bulk density, dust behaviour and dissolution rate, and only the second is sold for polypropylene fibre. More producers, plant locations and certifications are listed in the directory of calcium and zinc stearate manufacturers.

No price figure for calcium stearate is held in our verified data set, so none is quoted here. Price drivers for the metal soaps, which follow the fatty-acid feedstock rather than the calcium source, are tracked on calcium and zinc stearate prices.

How Do Metal Soaps Fit into the Lubricant Family?#

Calcium stearate is the highest-volume member of the metal soaps, the polar class of the lubricant family, which also contains the hydrocarbon waxes, the fatty-acid esters and the fatty amides. Melting point orders that family more usefully than the internal and external labels do: paraffin melts at 54 to 56 °C (129 to 133 °F), polyethylene wax at 102 to 110 °C (216 to 230 °F), zinc stearate at about 120 °C (248 °F), ethylene bis-stearamide at 138 to 144 °C (280 to 291 °F) and calcium stearate at about 160 °C (320 °F). The soap is therefore the last component of a PVC lubricant package to melt, which is what makes it the one that still holds the die wall at the hot end of the line.

The non-polar half of the lubricant family is covered under polymer waxes, where the paraffin, oxidized polyethylene, Fischer-Tropsch and montan grades that accompany calcium stearate in a pipe recipe are compared.

Calcium stearate outside plastics: E 470a, pharmaceuticals and cosmetics#

Outside plastics the same substance is a food additive, listed in the EU as E 470a (salts of fatty acids), and it appears in tablets and cosmetic powders as an anti-caking and flow agent. In the United States the equivalent recognition is the GRAS listing under 21 CFR 184.1229. This page covers calcium stearate as a plastics additive, and dietary, supplement and cosmetic questions are outside its scope: it does not answer whether calcium stearate is vegan, gluten free, dairy free or associated with any effect on the body, and no health or dietary advice is given here or anywhere above. The plastics reader takes one thing from the food-additive listing: a grade sold against a food-additive specification is bought on different numbers from a grade sold against a lubricant specification, which is the subject of the last question below.

Frequently asked questions about calcium stearate#

The 3 questions below are the ones that arrive most often from the plastics side of the search results, and each is answered from the data already given above.

Does calcium stearate dissolve in water?#

No: calcium stearate dissolves only to 0.004 g per 100 mL of water at 15 °C (59 °F), which is why it stays where it is dosed in a compound. That value, recorded by PubChem, puts it among the practically insoluble additives, and it is also the reason the soap is not extracted by an aqueous food simulant in the way a water-soluble additive would be.

Can calcium stearate cause plate-out or die build-up?#

It can contribute: the review of die drool by Mhlabeni, Jamiru and Mhike (2024) names metallic stearates in Ziegler-Natta polyolefins among the contributors, and Struktol advises reducing calcium stearate as much as possible for improved flow. Over-lubrication is the general mechanism, and the soap is one of 4 named contributors rather than the sole cause, alongside the low-molecular-weight polymer fraction, hexane extractables and volatile stabilizers. No plate-out threshold level for calcium stearate exists in our verified data set, so the effect is described rather than quantified. Deposits on tools and rolls are covered under plate-out in PVC processing.

What is the difference between a lubricant grade and a food or pharma grade?#

The CAS number is the same; the specification is not: plastics grades are bought on calcium content, ash, free fatty acid and filter index, while food and pharmaceutical grades are bought against pharmacopoeia or food-additive specifications. A plastics buyer also specifies the production route, because precipitated, direct-conversion, melt and COAD powders behave differently in a dry blend even at identical assay. No pharmacopoeia monograph is named here, because none is held in our verified data set. The one specification both sides share is the identity: calcium distearate, CAS 1592-23-0, 607.0 g/mol.