Mold Release Agents for Plastics and Composites: 6 Types, How They Work and Selection

Mold release agents stop a moulded plastic part from sticking to the tool, and they come in two forms that are not interchangeable: an internal mold release is compounded into the polymer, while an external release agent is applied to the mold surface; across both forms there are 6 chemical types, from metal soaps such as zinc stearate to bonded silicone coatings. Because only the internal form is a plastics additive, a compounder asks which ester, how many wt% and which FDA section, while a moulder asks sacrificial or semi-permanent, water-based or solvent-based, so which one does the job here? The best-documented number answers the compounder's version: 21 CFR 177.1580 caps pentaerythritol tetrastearate at 0.5 percent of the finished resin in food-contact polycarbonate, for use only as a mold release agent.

Mold release agents are one of the 43 families of plastic additives catalogued on this site, and they belong to the processing-modifier group with lubricants, polymer processing aids and slip agents; the three overlap, because the same zinc stearate that lubricates a PVC compound also releases an SMC part.

The sections below define the term, separate sacrificial from semi-permanent products, explain why parts stick, follow both mechanisms to the interface, work through the 6 types, match a type to each polymer and process, give the dosage, set out what over-dosing costs, name the test methods, map the FDA and EU routes and the D4, D5 and D6 restriction, and close with the producers and the substance list.

The 6 types differ in whether they travel through the polymer or sit on the tool, in the temperature they survive and in how they are cleared for food contact.

Internal release agents are plastics additives and are covered in full on this site. External release agents are process chemicals applied to the tool; they are covered here only where they are used to mold plastics and composites. Class list after Ullmann's, Release Agents (Lammerting 2000), via Wikipedia.

What Is a Mold Release Agent?#

A mold release agent is a chemical that stops a plastic or composite part from bonding to the mold it is formed in, and the four classes in industrial use are waxes, fatty esters, silicones and metallic soaps. That class list comes from Ullmann's article on release agents (Lammerting 2000), the source behind almost every secondary description of the family.

The same product is called several things in different plants, so which names mean the same thing? Release agent, mould release agent, parting agent, de-molding agent, form release, form oil, anti-adherent and releasing agent all name the same function, and "mould release agent" is the British spelling.

This page covers release agents used to mold plastics and composites. Concrete, plaster, bakery, die-casting and asphalt release agents share the head term but not the chemistry problem, and are out of scope.

Internal vs external mold release: what is the difference?#

An internal mold release is an additive compounded into the polymer, which migrates to the part surface during moulding, while an external release agent is a coating applied to the tool before moulding, so only the internal form appears on a formulation sheet. The four worked internal examples on this site are zinc or calcium stearate in sheet and bulk moulding compound, pentaerythritol tetrastearate in polycarbonate, calcium stearate in PLA and oleamide in polyolefins.

An internal release agent is a compounding decision with a food-contact consequence, because the additive travels with the material and its migration is regulated; an external release agent is a process decision with cleaning, bonding and painting consequences, because the film transfers to the part. Grades, carriers and dosing practice for the compounded form are set out on internal mold release agents.

Sacrificial vs semi-permanent release agents#

A sacrificial release agent is applied before every moulding cycle, while a semi-permanent release agent bonds to a clean mold surface and releases several parts per application, which is why the two are priced and measured differently. The distinction is about persistence on the tool, not about chemistry, because a wax and a siloxane can each be formulated either way.

External products are sold in 3 carrier systems, which decide handling rather than release performance:

• Water-based products carry the release chemistry in an aqueous emulsion or dispersion.
• Solvent-based products carry it in an organic solvent that flashes off on the hot tool.
• Co-solvent products combine water with an organic co-solvent.

How many parts a semi-permanent film releases is not held in our source library.

Why Do Moulded Parts Stick to the Tool?#

Moulded parts stick because the melt adheres to the hot metal of the tool, and the job of a release agent is to keep a low-adhesion layer between the two: Elvira Rabinovitch, I. Lacatus and James Summers showed in 1984, in the Journal of Vinyl Technology, that it is the polar additives, such as calcium stearate, that wet the metal and do this work. Their metal-release, fusion and microscopy data led them to call the plain "internal" or "external" label deficient in explaining performance at the metal wall, and to show that non-polar paraffin works by making the calcium stearate layer more fluid. Baerlocher states the same rule: external lubrication is the reduction of adhesion between polymer and metal, and that is what gives metal release.

Sticking has 4 recognised contributors in plastics moulding:

• Adhesion between the melt and the hot tool steel, the core mechanism a release agent addresses.
• Shrinkage onto cores and ribs, which grips the tool geometry.
• Thin walls and long flow paths, where the part cannot carry the ejection force.
• Sticky chemistries and filled compounds, such as SMC and BMC pastes, PLA and reacting polyurethane.

Chain length and polarity decide which additive does the work: polar groups such as hydroxyl, carboxylate and calcium carboxylate on C14 to C18 chains act inside the melt, while non-polar chains above C20 act at the metal wall. Tábi and Pölöskei showed in 2021 what happens when nothing does the second job: PLA parts moulded without a demolding additive stuck and broke on ejection. The internal and external balance is set out on processing lubricants for plastics, because a release agent that works too well also delays fusion.

How Do Mold Release Agents Work?#

Mold release agents work in 2 ways: an internal release agent dissolves in the melt and then migrates to the part surface, where it forms a thin low-adhesion layer, while an external release agent puts that layer on the tool instead of in the plastic. Peter Greven describes the internal route for metal soaps in SMC and BMC as migration to the surface of the material, and polydimethylsiloxane describes the external route: a siloxane film of low surface energy at the interface.

How thick that layer is, how fast it forms and what surface energy it reaches are not established here. Our source library holds no bloom-timing data, no surface coverage in µg/cm² and no surface-energy values for release agents, so the mechanism below is qualitative.

How does an internal mold release reach the part surface?#

An internal mold release dissolves or disperses in the melt and then moves to the polymer-metal interface, where it forms the release layer: Peter Greven describes metal soaps in SMC and BMC as migrating to the surface of the material. Pentaerythritol tetrastearate does the same in polycarbonate, as a high-molecular-weight, low-polarity ester that blooms to the mold interface.

Three properties set how readily it gets there. Melting point comes first, because the additive has to be molten at process temperature: zinc stearate melts at about 120 °C in Baerlocher's grade description, against 179 °C for pure calcium stearate and 140 to 165 °C for commercial grades. Polarity comes second, because polar species stay in the melt and less polar species move to the metal. Particle fineness comes third, and Peter Greven reports that precipitated metal-soap grades release particularly well. The general rules of blooming in plastics apply to every migrating additive, release agents included.

How does an external release agent work?#

An external release agent forms a low-surface-energy film on the tool itself, most often a siloxane film, so the melt never touches bare steel. The film is a barrier on the tool, not a lubricant in the polymer, so it never appears on a formulation sheet.

Reapplication separates the two product forms. A sacrificial coating is applied before every moulding cycle and is consumed with the part; a semi-permanent product bonds to a clean mold surface and survives several cycles. That wording is the limit of what our source library supports, and no cleaning procedure is set out here.

6 Types of Mold Release Agents for Plastics#

The 6 types of mold release agents for plastics are metal soaps, ester release agents, fatty amides, waxes, silicones and external release systems; the first four are compounded into the polymer, silicones are used both ways, and the sixth is applied to the tool. Ullmann's names waxes, fatty esters, silicones and metallic soaps as the industrial classes; the fatty amides are listed separately here because the FDA regulates them by name as release agents in 21 CFR 178.3860. The sixth type is a product form rather than a chemistry.

1. Metal soaps: zinc, calcium and magnesium stearate#

Metal soaps are the salts of stearic acid with zinc, calcium or magnesium, and they release by migrating to the part surface, which is why they dominate SMC and BMC moulding and appear in almost every styrenic and polyamide compound. Zinc stearate is the preferred internal release agent in sheet and bulk moulding compound because it melts lower than the calcium soap, and precipitated grades release best because of their fineness. Magnesium stearate is a lubricant and release agent for ABS and polyamide and a dusting agent against surface adhesion in ABS, dosed at 0.3 to 3 parts on Struktol's technical data sheet. Zinc stearate and EBS in styrenics are covered with additives for polystyrene.

At the same dosage, coarser stearates raise the paste viscosity of an SMC or BMC compound less, while finer grades reach the same release effect at a lower dosage. In the EU the whole class travels one route, because metal soaps have no FCM number of their own. Production routes, metal contents and the filter index are compared on metal stearates.

Zinc stearate#

Zinc stearate (CAS 557-05-1) is the metal soap most used as an internal mold release, because it melts at about 120 °C and therefore spreads evenly through the melt before migrating to the part surface. It is EC 209-151-9, C36H70O4Zn, 632.3 g/mol, density 1.095 g/cm³, melting at 130 °C in PubChem and NIOSH data, 118 to 122 °C in Peter Greven's grade range and 115 to 125 °C in Struktol's, with 10.4 to 11.3 % zinc and the trade names Zincum (Baerlocher), LIGASTAR ZN (Peter Greven) and Struktol Zinc Stearate.

Struktol gives 0.5 % as a general level in most plastics, and the substance also serves polystyrene, EPS and filled masterbatch: Kgomotso Radebe, John Wesley-Smith, Walter Focke and Shatish Ramjee reported in 2022 that 1.0 wt% zinc stearate with 3 wt% wax in a 60 wt% calcium carbonate LLDPE masterbatch returned the melt viscosity to just above that of the neat polymer, otherwise three times higher. Zinc stearate is GRAS under 21 CFR 182.8994, reaches EU food contact through FCM 106 with an Annex II zinc limit of 5 mg/kg, and is not classified in 61.3 % of 2,108 CLP notifications, with minority notifications for H400, H413 and H335.

Calcium stearate#

Calcium stearate (CAS 1592-23-0) is used as a release agent in unsaturated-polyester SMC and BMC, in polyamide and in PLA, where Tamás Tábi and Kornél Pölöskei (2021) found that 1 wt% removed the stuck and broken parts from injection moulding. It is EC 216-472-8, C36H70CaO4, 607.0 g/mol, melting at 179 °C as a pure substance and at 140 to 165 °C in commercial grades, with 6.3 to 7.9 % calcium and the trade names CEASIT (Baerlocher) and LIGASTAR CA (Peter Greven).

Calcium stearate does three jobs, which is why it is filed under lubricants: it lubricates PVC, it scavenges acid in polyolefins at 0.05 to 0.20 %, where Peter Greven reports that 500 ppm kept a steel plate from corroding in a polypropylene test, and it releases parts in SMC, BMC and PLA. It is GRAS under 21 CFR 184.1229 and prior-sanctioned under 181.29, and the CAS number printed in 184.1229, 1529-23-0, is a typo for 1592-23-0.

2. Ester release agents: PETS, GMS, EGDS and complex esters#

Ester release agents are fatty acid esters of polyols and glycols, such as pentaerythritol tetrastearate (PETS), glycerol monostearate (GMS) and ethylene glycol distearate (EGDS), that bloom to the tool interface and release without the metal content of a soap. GMS is an internal lubricant for clear PVC at 0.5 to 1.5 phr in rigid and 0.5 to 1.0 phr in flexible compounds, and it is dosed at 0.15 % in LDPE, 0.3 % in HDPE and 0.05 to 0.5 % in polypropylene. EGDS has a dropping point of 63 to 73 °C and runs at 0.5 to 1.5 phr in rigid PVC, and stearyl stearate is Peter Greven's example of a waxy lubricant ester.

Polarity places the ester on one side of the interface or the other: Peter Greven's rule is that the more polar the ester, the more it works inside the melt, and that lowering the polarity moves the effect outwards to the metal. The full ester family, including complex esters and montan esters, is compared on ester lubricants.

PETS in polycarbonate#

PETS is the standard internal mold release for polycarbonate, and 21 CFR 177.1580 caps it at 0.5 wt% of the finished resin, for use only as a mold release agent. PETS is CAS 115-83-3, EC 204-110-1, C77H148O8 at 1,202.0 g/mol, a high-molecular-weight, low-polarity ester that blooms to the mold interface, and the polycarbonate profile used on this site pairs the 0.5 wt% release limit with an extractives limit of 0.15 wt%.

In the EU, PETS is covered by FCM 880, fatty acids C8-C22 esterified with pentaerythritol, which carries no SML, so the generic specific migration limit of 60 mg/kg and the overall migration limit of 10 mg/dm² apply. It carries 3 active REACH registrations, is not classified in 416 of 416 CLP notifications, and Peter Greven holds FDA food contact notification FCN 001963 for saturated pentaerythritol esters.

3. Fatty amides: oleamide, erucamide, stearamide and EBS#

Fatty amides are the only release chemistry the FDA regulates by name: 21 CFR 178.3860 lists erucamide, oleyl palmitamide, stearyl erucamide and saturated fatty acid amides as release agents for polymers used at good-manufacturing-practice levels. The same section carries two numeric outliers, rice bran wax at up to 1.0 % by weight for dry foods only and N,N'-dioleoylethylenediamine (EBO) in PVC film at up to 0.055 mg per square inch. Ethylene bis stearamide (EBS, CAS 110-30-5, C38H76N2O2, 593.0 g/mol) melts at 135 to 146 °C, is classed by Baerlocher as an external PVC lubricant at 138 to 144 °C, and works as lubricant, dispersant, release agent and antiblock additive in ABS, PS, PVC and polyolefins at 0.5 to 2.0 % as a blend.

Dosage, not chemistry, decides whether an amide is a slip agent or a release agent: oleamide is used at about 0.05 % in films and above 0.5 % for mold release, which is how Struktol's TR 121 sheet sells it. Oleamide itself is not named in 21 CFR 178.3860, and its US clearances sit in 175.105 for adhesives and 178.3910 as a surface lubricant on metallic articles. The same amides at film dosage are slip additives for plastic film, where the target is a low coefficient of friction rather than release.

4. Waxes: montan esters, PE and oxidised PE wax, paraffin and Fischer-Tropsch wax#

Waxes release by staying at the melt-metal boundary rather than dissolving in the polymer, and the two that matter most are the refined montan esters used in engineering plastics and the oxidised polyethylene wax used at only 0.07 to 0.3 phr in PVC. Montan wax (CAS 8002-53-7) is a solvent extract of lignite, 62 to 68 % esters, 22 to 26 % acids and 7 to 15 % alcohols and hydrocarbons, melting at 82 to 95 °C; its useful derivatives come from Gersthofen oxidative refining to montanic acids and partial esterification with ethylene glycol or 1,3-butanediol, with or without calcium neutralisation. Polyethylene wax (CAS 9002-88-4) is an external lubricant of up to about 10,000 g/mol, while paraffin and Fischer-Tropsch waxes sit at 200 to 1,000 g/mol, the Fischer-Tropsch grades produced mainly by Sasol (Mhlabeni, Jamiru and Mhike 2024).

Food contact splits the class into four routes. Montan esters are cleared as lubricants in PVC food-contact articles under 21 CFR 178.3770 with a dropping point of 76 to 105 °C, and in the EU as FCM 529 and 67; oxidised PE wax (CAS 68441-17-8) is FCM 811 with an SML of 60 mg/kg and 21 CFR 177.1620; plain PE wax is FCM 549 with no SML; refined low-viscosity paraffin is FCM 93 with an SML of 0.05 mg/kg and is not permitted for fatty foods. Struktol adds that paraffin is not recommended for articles that are to be printed. Molecular mass, dropping point and the differences between the wax families are set out on polymer waxes.

5. Silicones: PDMS oils, emulsions and masterbatch#

Silicone release agents are polydimethylsiloxane (PDMS) oils, emulsions and masterbatches that put a low-surface-energy film between the melt and the tool, and they are the only type used both externally and internally. PDMS is CAS 63148-62-9, and the same chemistry serves as a slip and lubricant additive in masterbatch and as the base of polyether-grafted processing aids. The FDA lists polyoxyethylene-grafted PDMS (CAS 68937-54-2) as an extrusion aid for olefin polymers at up to 0.3 wt% under 21 CFR 177.1520, and EU 10/2011 covers PDMS as FCM 575 for grades above 6,800 Da with a viscosity at 25 °C of at least 100 cSt.

The compliance issue is not the polymer but what is left in it: residual cyclosiloxanes D4, D5 and D6 in silicone mixtures are restricted at 0.1 % by weight from 6 June 2026 under REACH Annex XVII entry 70, with derogations, and all three are on the SVHC Candidate List as PBT or vPvB. Silicone release agents are not banned. Grades, emulsions and the compliance position are covered on silicone mold release agents.

6. External release systems: semi-permanent coatings, sacrificial waxes and carriers#

External release systems are the products applied to the tool rather than to the polymer: silicone oils and emulsions, semi-permanent reactive silane and siloxane coatings, wax-based products and fluoropolymer-based products, supplied in water, solvent or co-solvent carriers. A semi-permanent product bonds to a clean mold surface and releases several parts per application; a sacrificial product is applied before every cycle.

The four chemistries above are the only ones our source library supports. Polyvinyl alcohol film-forming release agents, carnauba and paste waxes and dry-film coatings based on tungsten disulfide or PTFE all appear in the market, but no verified data on them is held here, and neither are VOC, transfer, build-up or cleaning figures, so this page names no product and gives no application instructions.

External release agents are process chemicals rather than plastics additives, so this site covers them only where they are used to mold plastics and composites: injection moulding, polyurethane and RIM, composites in epoxy, unsaturated polyester and fiberglass, rotomolding and thermoforming.

Which Mold Release Agent Suits Each Polymer and Process?#

The release agent follows the polymer and the process: PETS for polycarbonate, zinc stearate for SMC and BMC, calcium stearate for PLA, zinc or magnesium stearate with EBS for styrenics, montan esters for polyamide, and external silicone or wax systems for polyurethane and composites. Process temperature narrows the choice as much as the polymer does, because an additive that is not molten at the tool face cannot form a release layer. The table below sets out the practice for 10 polymers and processes, with the number this site can source for each.

Mold release agents for injection molding#

Injection moulding uses both routes: an internal release agent chosen with the compound (PETS in polycarbonate, calcium stearate in PLA, zinc or magnesium stearate and EBS in styrenics) or an external release agent sprayed on the tool when the formulation is fixed. Magnesium stearate has a second role in this process, as a dusting agent against surface adhesion in ABS. Grades and dosing for moulding shops are set out on mold release agents for injection molding.

An internal release travels with the compound and needs a food-contact check before it reaches a packaging or appliance part; an external release is a per-cycle or per-run process cost, needs no change to the material specification and has to suit whatever happens to the part afterwards.

A part that releases easily also refuses paint, and the rest of the moulding package is on additives for injection molding.

Mold release for polycarbonate and engineering plastics#

Polycarbonate is the clearest case in the whole family: PETS is the standard internal mold release, and food-contact grades are capped at 0.5 wt% of the finished resin under 21 CFR 177.1580. The same profile pairs that ceiling with an extractives limit of 0.15 wt%, so the release level sits inside a surface-chemistry budget for the resin. The full PC package, including UV absorbers and anti-drip PTFE, is on additives for polycarbonate.

Polyamide, PET and PBT move towards the waxes and the higher esters. Montan esters are the classic release lubricant for engineering plastics, cleared in PVC food-contact articles under 21 CFR 178.3770 with a dropping point of 76 to 105 °C, and PET and PBT compounds use pentaerythritol and montan esters. Struktol's TR 063A, a special ester for polyamide compounding, runs at 0.2 to 2.0 % and is sold to reduce die bearding and drool rather than to release a part.

Montan and pentaerythritol ester grades for nylon are covered with additives for nylon.

Mold release for SMC, BMC and fiberglass composites#

Sheet moulding compound and bulk moulding compound use zinc stearate as the internal release agent, because it melts lower than calcium stearate and migrates to the part surface during the press cycle. Calcium stearate is also used, and both are supplied as dedicated SMC grades, such as Baerlocher's ZINCUM SW 1626 and CEASIT SW 1725, with Peter Greven noting that precipitated grades release particularly well because they are very fine.

At the same dosage, a coarser stearate raises the paste viscosity less, while a finer grade reaches the same release effect at a lower dosage, and Peter Greven's Brookfield comparison of grades was run at 1.23 wt%, which is a test level rather than a recommendation. Fiberglass and epoxy tooling is dominated by semi-permanent external coatings instead, and no gelcoat or epoxy release data is published here beyond that. Semi-permanent coatings, sealers and the fiberglass and epoxy side are covered on mold release agents for composites.

Mold release for polyurethane, RIM and rotational molding#

Polyurethane and reaction injection moulding are external-release processes in practice: wax and silicone emulsions are applied to the tool, because the reacting system leaves little room for a compounded additive. Rotational moulding sits in the same group, inside this site's external-release scope, and the wider PU formulation picture is on additives for polyurethane and TPU.

Internal mold release systems for polyurethane exist and are the subject of a patent literature, but no chemistry or level for them is stated here, because no primary source has been verified. The polyurethane case is treated separately on mold release agents for polyurethane.

Mold release for PLA and bio-based plastics#

PLA is the bio-based case with a published number: Tamás Tábi and Kornél Pölöskei (2021), at the Budapest University of Technology and Economics, used 1 wt% calcium stearate as a demolding agent in PLA injection moulding and reported in Periodica Polytechnica Mechanical Engineering that stuck and broken parts disappeared. The additive is the same GRAS metal soap used in SMC and BMC, which makes it an unusually easy specification to clear: calcium stearate is GRAS under 21 CFR 184.1229 and reaches EU food contact as a salt of stearic acid.

That 1 wt% figure belongs to PLA and to that study. It is not carried over here to PHA, PBS, PBAT or starch blends, because no release data is held for them. The rest of the PLA package, from nucleating agents to chain extenders, is on additives for PLA.

How to select a mold release agent in 6 steps#

Select a mold release agent in 6 steps: decide between an internal and an external product, match the polymer and the process temperature, check what happens to the part surface afterwards, screen the food-contact clearances, check the silicone restriction, and then set the lowest level that releases.

1. Decide whether the release agent can go into the compound at all, or whether the formulation is fixed and only an external product is possible.
2. Identify the polymer and the process temperature, since polycarbonate and polyamide need heat-stable esters while SMC and BMC need a soap that melts below the press temperature.
3. Check what happens to the part afterwards, because painting, bonding, printing, welding and plating all fail on an over-released surface.
4. Screen the food-contact clearances in each market: 21 CFR 177.1580 for PETS in polycarbonate, 178.3860 for the amides, 178.3770 for montan esters, the GRAS listings for the stearates and the EU FCM routes.
5. If a silicone product is in scope, check the D4, D5 and D6 content of the mixture against REACH Annex XVII entry 70.
6. Set the level at the lowest that releases, then confirm it on the tool and watch for plate-out and surface defects.

Steps 3 and 4 should be treated as gates, not checks, because both produce rejects weeks after the trial. The same logic for every family is laid out in how to select plastic additives.

How Much Internal Mold Release Is Needed? Dosage in wt% and phr#

Internal mold release agents are dosed in tenths of a percent to a few percent: zinc stearate at about 0.5 wt% as a general level, calcium stearate at 1 wt% in PLA, magnesium stearate at 0.3 to 3 parts in ABS, and PETS capped at 0.5 wt% in food-contact polycarbonate. Only the last of those is a legal ceiling; the others are supplier recommendations or single study values, and the table below labels which is which.

PVC formulations are written in parts per hundred resin, polyolefin and styrenic recipes in weight percent or ppm, and ABS release levels are quoted in parts on the supplier sheet, so each row above keeps the unit its source uses. Weight percent equals the phr of the ingredient divided by the total phr, multiplied by 100, and units and conversions between phr, wt% and ppm are set out on PHR (parts per hundred resin).

A stearate can enter the compound as a powder, in a one-pack or through a masterbatch. Compare levels and cost in use with the additive dosage and cost-in-use calculator.

What Goes Wrong: Over-Dosing, Plate-Out and Surface Defects#

Too much release agent causes 4 recognisable problems: haze, exudation, poor printing and bonding, and deposits on the tool, and all four come from the same cause, an additive present at more than the surface needs. Baerlocher's lubricant performance matrix records the first three against externally acting lubricants: they can cause haziness, they can cause exudation at high dosage, and they can worsen printability, weldability and adhesion, while internally acting products do not. The fourth, plate-out, is the PVC-specific deposit of formulation components on calender rolls, dies and screws, and over-lubrication and incompatible external lubricants both contribute to it.

A part that sticks and a part that will not take paint are two ends of one scale, which is why the release level is set as low as the tool allows. Rabinovitch, Lacatus and Summers made the deeper point in 1984: the internal and external labels describe where an additive tends to act, not what it does in a given formulation, so a package is rebalanced as a whole. The PVC-specific deposit problem is covered on plate-out in PVC processing.

How often any of this happens is not quantified here, because no failure-rate or scrap-rate data for release problems is held here. Defect-by-defect diagnosis is on troubleshooting additive-related defects.

How Is Mold Release Performance Tested?#

There is no single mold-release test standard: release is confirmed on the tool, and the laboratory work around it uses 7 proxy methods, from the dropping point of the additive to the haze of the part. No ejection-force, demolding-force, release-force or peel standard is held in our source library. Every method on this site is indexed under testing plastic additives.

Release performance is claimed in every product brochure in this category and measured by a standard in none of them, so a moulding trial on the real tool remains the test that decides.

Laboratory work confirms the additive is fit for the process, through dropping point, torque and melt flow, and afterwards how much of it reached the part. Confirming how much release agent is in a finished part is a deformulation job, covered on additive analysis and deformulation.

How Are Mold Release Agents Regulated?#

Mold release agents are regulated through 4 routes: the FDA's release-agent and polymer sections (21 CFR 178.3860, 177.1580 and 178.3770), the EU food-contact positive list of Regulation (EU) No 10/2011, the REACH restriction on residual cyclosiloxanes in silicone products, and the general REACH and CLP duties of each substance. Only the first two apply to the internal additives as such; the third is a mixture rule that reaches external silicone products, and the fourth applies to every substance placed on the EU market whatever it is used for.

None of the four supports the phrase "FDA approved": a substance is listed in a section, cleared up to a limit, or generally recognised as safe under a named part. Other instruments are summarised in plastic additive regulations.

FDA: 21 CFR 177.1580, 178.3860 and 178.3770#

The FDA regulates mold release agents in three places: 21 CFR 178.3860 lists the release agents themselves, 21 CFR 177.1580 caps PETS in polycarbonate at 0.5 percent of the finished resin, and 21 CFR 178.3770 covers refined montan esters as lubricants in PVC food-contact articles. Section 178.3860 is titled "Release agents" and clears its substances for use in polymeric resins that contact food at good-manufacturing-practice levels, with two exceptions that carry numbers. How the 21 CFR parts fit together is mapped on FDA food contact rules.

Where no specific SML is listed, the generic 60 mg/kg specific migration limit and the overall migration limit of 10 mg/dm² apply.

The stearates take a different US route, because they are food ingredients before they are additives. Zinc stearate is GRAS under 21 CFR 182.8994, calcium stearate under 184.1229, magnesium stearate under 184.1440, stearic acid under 184.1090 and GMS under 184.1324, and calcium, magnesium, aluminium and sodium stearates also appear as prior-sanctioned stabilizers in 21 CFR 181.29. One transcription point matters: 184.1229 prints CAS 1529-23-0 for calcium stearate, a typo for 1592-23-0. The full site-wide limit table is on specific migration limits (SML).

EU 10/2011: how metal soaps and esters are authorised#

Metal soaps have no FCM number of their own in the EU: zinc, calcium and magnesium stearate are authorised as salts of stearic acid, which is FCM 106, under Article 6(3)(a) of Regulation (EU) No 10/2011. That article covers the salts of every authorised acid, which is why a stearate compliance file points at the acid entry, and the migration-limit system is explained on EU 10/2011. The esters, amides and waxes do carry their own entries: FCM 880 for pentaerythritol esters, 53 for GMS, 89 for EGDS, 250 for EBS, 271 for erucamide, 335 for oleamide, 529 and 67 for montan wax and its acids and esters, 549 and 811 for PE and oxidised PE wax, and 575 for PDMS.

The metal, not the soap, sets the numeric limit. Annex II gives zinc an SML of 5 mg/kg, set by Regulation (EU) 2020/1245, aluminium 1 mg/kg, lithium 0.6 mg/kg and barium 1 mg/kg, while calcium, magnesium, sodium and potassium carry no metal limit at all. Where a substance has no specific migration limit, the generic SML of 60 mg/kg and the overall migration limit of 10 mg/dm² apply.

D4, D5 and D6 in silicone release agents (REACH Annex XVII entry 70)#

Silicone release agents are the one part of this family with a dated EU restriction: since 6 June 2026, the cyclosiloxanes D4, D5 and D6 may not be placed on the market in mixtures at 0.1 % by weight or more, under REACH Annex XVII entry 70 as amended by Regulation (EU) 2024/1328. The restriction is on the residual cyclosiloxane content of the mixture, not on silicone release agents as a product category, and the three substances are on the SVHC Candidate List as PBT or vPvB.

Two later dates and a set of derogations qualify that. Leave-on cosmetics follow from 6 June 2027 and medical devices and medicinal products from 6 June 2031, while derogations cover industrial uses and defined residues in silicone polymer mixtures: up to 1 % for adhesion, sealing, gluing and casting, up to 0.5 % D4 or 0.3 % D5 and D6 for protective coatings, and 0.2 % for devices. Which category a professional mold-release spray or emulsion falls under is not settled in our source library, so a buyer works from the supplier's declaration for the specific product. Entry 70 sits with the other restrictions on REACH Annex XVII.

REACH, CLP and SVHC status of mold release agents#

No internal mold release agent in this family is a substance of very high concern: the metal soaps, PETS, EBS and the ester and wax lubricants are absent from the Candidate List, Annex XIV and Annex XVII as of September 2026, and the only SVHC entries in the family are the residual cyclosiloxanes D4, D5 and D6 in silicone products. The three status questions a buyer asks separate cleanly:

• Registration: ECHA CHEM showed 13 active dossiers for zinc distearate on 22 September 2026, plus 76 under "Fatty acids, C16-18, zinc salts", against 10 for calcium distearate, 25 for GMS, 9 for EBS, 6 for EGDS, 4 for stearyl stearate and 3 each for PETS and montan wax, the montan entries all Article 18 intermediates. PE wax, oxidised PE wax and PDMS are exempt as polymers, and no active dossier was found for magnesium stearate, which stays an open item here.
• Restriction and SVHC status: clean for every internal release substance, with the cyclosiloxanes as the single exception.
• Classification: the CLP data are notifier aggregates, not harmonised classifications. Calcium stearate is not classified in 85.5 % of 3,808 notifications, zinc stearate in 61.3 % of 2,108, magnesium stearate in 54.9 % of 510, EBS in 76.3 % of 1,846 and PETS in all 416 of 416.

The zinc aquatic notifications are the ones that reach a label, at about 31 % H400 and 23 % H413. Registration duties are explained in REACH and plastic additives.

Who Makes Mold Release Additives? Suppliers and Trade Names#

The internal release additives on this page are made mainly by metal-soap and wax producers: Baerlocher (CEASIT, ZINCUM), Peter Greven (LIGASTAR), Struktol, PMC Biogenix (Kemamide), Croda, Lonza and Clariant (Licowax, Licolub). The list is shorter than the market: the dedicated external-release houses that dominate the search results for this term are not listed here, because this site publishes company data only where it has been verified, and they will be covered once that work is done.

Baerlocher is family-owned and has been for more than 200 years, with about 1,150 employees; its SMC and BMC release grades are ZINCUM SW 1626 and CEASIT SW 1725. No market size, growth rate or price is published on this page, because none has been verified.

Stearate producers are compared on calcium and zinc stearate manufacturers and suppliers, and wax and ester producers are tendered separately, because soap and wax come out of different plants.

Indian producers are listed with plastic additive manufacturers and suppliers in India, which is where much of the oleochemical route to stearates and amides sits.

Complete List of Mold Release Substances (12 Pages)#

The complete list below gives the 12 substance pages on this site that are used as mold release agents, with their type, CAS number, release use and EU authorisation route; none of them is filed under the mold-release family, because every one of them is also a lubricant, a slip agent or an antistat. Rows follow the page's type order.

Stearic acid, paraffin wax, polyethylene wax, oxidised polyethylene wax, Fischer-Tropsch wax, ethylene bis oleamide and stearamide are also used in release packages and are listed under the lubricant and slip families. The 12 rows above are the substances with an explicit release function in their record or a named FDA release route.

Every other additive, from antioxidants to pigments, is searchable in the plastic additives database.

Mold Release Outside Plastics: Concrete, Plaster, Rubber and Household Mould#

The phrase "mold release agent" is used in concrete casting, plaster work, baking, die casting and hobby resin moulding as well as in plastics, and only the plastics and composites uses are covered on this site. Those fields solve a different problem with different chemistry, even where the product on the shelf looks similar. What they share is the physics of a substance travelling to a surface, and the migration and surface behaviour of every such additive are on additive migration in plastics.

Is a concrete or plaster release agent the same thing?#

No: a concrete form release oil and a plaster release agent solve a different problem, the mechanical and chemical bond between a curing mineral and formwork, and neither is a plastics additive. They are separate product categories with their own retailers, and the general encyclopaedic description of release agents is dominated by them rather than by plastics. Nothing on this page transfers to either.

Can you use Vaseline, WD-40 or cooking spray as a mold release?#

These are hobby-casting questions rather than production questions, and our source library holds no data on petrolatum, penetrating lubricants or cooking sprays as release agents, so it states no view on them.

In a plant the choice runs between a compounded internal release agent with a declared identity, a dosage in wt% or phr and a food-contact status, and a formulated external product with a supplier declaration behind it.

Does "mold release" have anything to do with household mould?#

No: "mold" here is the steel or composite tool a part is formed in, not the fungus, and nothing on this page relates to removing mould from a house or from a plastic surface. US English spells the tool and the fungus the same way, which is the only connection between them.

Do release agents affect painting, bonding and recycling?#

Yes for the part surface: Baerlocher's performance matrix records that external-acting lubricants can worsen printability, weldability and adhesion, and can cause exudation at high dosage, which is why release levels are set as low as they can be. A part that has just released perfectly carries an additive layer on its face, and paint, ink, adhesive and ultrasonic welds all have to reach through it.

The recycling question is not answered here, because our source library has no release-agent recyclate data. General rules on how additives affect recyclability are on design for recycling.