Mold Release Agents for Injection Molding: 5 Types, Dosage and Selection

Mold release agents for injection molding are either internal additives, mainly metallic soaps, fatty esters and fatty amides compounded into the plastic at roughly 0.05 to 3 wt%, or external coatings sprayed on the tool, and only the first kind is a plastic additive. That distinction decides who buys it, the compounder or the molding shop, so which of the two solves a sticking part, and at what level? Five chemical classes cover almost every internal grade, and the right one is set by the polymer's melt temperature, its polarity and what happens to the part after it leaves the tool.

Release agents sit in the processing-modifier group of plastic additives, next to lubricants, slip agents and processing aids. Internal mold release migrates or blooms to the part surface as the melt cools, separating it from a lubricant added only to reduce internal friction, and it is dosed, declared and regulated differently as a result.

This page covers the five internal mold release classes, which class and grade suits polycarbonate, ABS, polyamide, POM, polyolefins, PLA and rigid PVC, how much to dose in wt% or phr, how the additive is delivered, what it does to painting, printing and welding downstream, and which grades clear Regulation (EU) No 10/2011 or the matching section of 21 CFR.

Key figures

• 5 chemical classes of internal mold release: metallic soaps, fatty acid esters, fatty acid amides, waxes and silicones
• 0.5 wt% is the FDA ceiling for PETS in food-contact polycarbonate (21 CFR 177.1580)
• 1 wt% calcium stearate eliminated stuck and broken parts in injection-molded PLA (Tábi and Pölöskei, 2021)
• 1.0 wt% is the EU intended-use level for injection-molded C14-C18 alkanamides, against 0.2 wt% for film (FCM 1065, EFSA 2017)

Why Do Injection-Moulded Parts Stick in the Mould?#

Injection-molded parts stick because the polymer wets the hot tool steel and adheres to it as it solidifies, so demolding needs a boundary layer between the part surface and the cavity wall. An internal mold release agent builds that layer itself, migrating through the melt and blooming to the part surface as its solubility in the polymer drops on cooling, while an external agent coats the steel directly instead. Whether an additive acts at the polymer interface or the metal interface depends on chain chemistry: polar carboxylate and ester head groups on chains around C14 to C18 wet the tool steel and act internally, while longer, non-polar chains above C20 sit at the metal interface.

The hub on mold release agents for plastics and composites covers the same five classes across all molding processes, from injection and compression to SMC and BMC. Injection molding adds its own constraints: shot-to-shot repeatability, a melt running from 180 degrees C in polyolefins to above 300 degrees C in polyamide, and, on a growing share of parts, a food-contact or medical specification that limits which grade can be used at all.

What makes a moulded part release from the cavity?#

A molded part releases when a thin, low-adhesion layer sits between the polymer and the tool, and an internal release agent builds that layer itself: it is only partly soluble in the melt, so it diffuses to the surface as the part cools. The additive is dissolved at processing temperature, but its solubility falls as the part cools toward the mold temperature; once supersaturated, the excess diffuses to the surface at a rate set by its own diffusion coefficient, a mechanism Nouman and colleagues described in Polymer Degradation and Stability (2017) for additive blooming generally. Peter Greven's plastics brochure describes the same behaviour in metal soaps directly: they "migrate to the surface of the material" during and after molding.

Internal release works in 3 steps:

1. The additive dissolves into the polymer melt at processing temperature, distributed evenly at its dosed level.
2. The additive becomes supersaturated as the melt cools, because its solubility falls faster than the polymer's own temperature.
3. The additive diffuses to the part surface and forms a low-adhesion film against the tool steel, which releases the part at ejection.

This diffusion behaviour is the same phenomenon covered in depth under blooming and exudation, which sets out the solubility-parameter and molecular-weight levers a formulator uses to control it.

Which sticking problems can an additive fix, and which cannot?#

An internal mold release agent changes the chemistry at the part surface, so it fixes sticking that comes from adhesion between polymer and steel; it does nothing about sticking from tool geometry or molding settings. A molder should rule out tooling and process causes first, since a release additive cannot compensate for a mold with no exit path for the part.

What an internal release additive changes:

• The surface chemistry of the molded part, by adding a low-adhesion film between polymer and steel
• The friction between the part and the cavity or core at ejection
• The bond strength between the melt and the tool surface as the part solidifies

What an internal release additive does not change:

• Draft angles and undercuts on the tool
• Surface texture, polish direction and vent placement
• Ejector layout and ejector force
• Packing pressure and mold temperature settings

Overdosing adds only the side effects of over-lubrication, such as exudation, haze and worse printability, plus blooming or chalking from an additive above its solubility limit. Faults tracing to the compound rather than the tool are catalogued under additive-related defects.

Internal vs External Mold Release Agents: Which One Belongs in Injection Molding?#

Internal mold release agents are compounded into the plastic and work on every shot without operator action, while external release agents are sprayed or wiped on the tool and are process chemicals rather than plastic additives. Internal release suits high-volume injection molding, food-contact parts and any shop that wants release performance without an operator step between cycles; external release suits low-volume runs, prototype tooling and parts where the compound cannot carry an additive. Many molders on forums such as r/InjectionMolding argue that the better fix is a tool designed so that no release agent is needed at all, and an internal release agent survives that preference best, since it is built into the material and never reaches the operator as a separate step.

What is an internal mold release agent?#

An internal mold release agent is an additive compounded into the plastic itself, which migrates to the part surface during molding and lowers the adhesion between part and tool. It is added at the compounding stage, as a powder blended before extrusion or as a masterbatch dosed at the hopper, and stays active for the life of the resin rather than being reapplied cycle by cycle. Ethylene bis stearamide shows how broad the category can be inside one compound: it functions as a lubricant, dispersant, release agent and antiblock agent at the same time.

Zinc stearate shows how grade selection works inside the class: it is preferred in sheet and bulk molding compound (SMC and BMC) because its melting point is lower than calcium stearate's, and precipitated grades release best because their fine particle size gives more surface area for migration. A finer metal-soap particle reaches the same release effect at a lower dosage than a coarse one. All of the chemistries sold as internal mold release agents are compared on their own page, across every molding process.

What is an external mold release agent?#

An external mold release agent is a coating applied to the cavity rather than to the plastic, most often a silicone, wax or fluorochemical film in a water, solvent or co-solvent carrier. It sits on the tool surface, not in the resin, and it transfers a thin film to the part at ejection instead of migrating out of the polymer itself. External release agents are process chemicals, not plastic additives, so this page covers them only as they are used to mold plastics.

Our source library holds no verified data on named external release brands, spray equipment or their certifications, so this page names no supplier and states no dosage for that side of the market; a buyer comparing them should go directly to their technical data sheets. Silicone-based external release, built on polydimethylsiloxane, carries its own compliance question because D4, D5 and D6 cyclosiloxane residues are restricted; the mechanism and the compliance date are covered under silicone mold release agents rather than repeated here.

Sacrificial and semi-permanent release coatings#

Sacrificial release coatings are reapplied before every molding cycle, while semi-permanent release agents bond to a clean tool surface and carry several releases per application.

A semi-permanent grade trades a slower build-up step, cleaning and bonding a fresh tool surface, for dozens of releases before the next application, which is the reason production shops favour it over a sacrificial spray once a tool is running steady-state.

What Are the 5 Types of Internal Mold Release Agents?#

The 5 types of internal mold release agents used in injection molding are metallic soaps, fatty acid esters, fatty acid amides, waxes and silicones, with metallic soaps and esters doing most of the work in molded thermoplastics. Ullmann's Encyclopedia groups release agents into waxes, fatty esters, silicones and metallic soaps; the fatty amides form a fifth class here because the US FDA lists them as release agents in their own right under 21 CFR 178.3860. The classes below are ordered by importance in injection molding, metallic soaps first and silicones last.

Melting and dropping points are supplier and PubChem values for representative grades; check the technical data sheet of the grade you buy.

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

Metallic soaps are the calcium, zinc and magnesium salts of stearic acid, and they release a molded part by migrating to its surface, where the polar carboxylate group wets the tool steel instead of the polymer. Zinc stearate, CAS 557-05-1, 632.3 g/mol, contains 10.4 to 11.3% zinc and melts at 130 degrees C (PubChem) or 115 to 125 (Struktol); its low melting point "lets it spread evenly when heated" (Baerlocher), and Ullmann's calls it the most powerful mold release agent among the metal soaps, at a general level of 0.5 wt%.

Calcium stearate, CAS 1592-23-0, 607.0 g/mol, contains 6.3 to 7.9% calcium and melts at 179 degrees C pure against 140 to 165 commercial; it also works as an acid scavenger in polyolefins at 0.05 to 0.20%. Magnesium stearate, CAS 557-04-0, 591.2 g/mol, contains 4.0 to 4.8% magnesium and is used in ABS at 0.3 to 3 parts, doubling as a dusting agent against surface adhesion. A coarser stearate raises paste viscosity less at a given dosage, while a finer one reaches the same release effect at a lower dosage, a trade-off Peter Greven documented with a Brookfield test at 1.23 wt%. Grades, metal content and hazard notifications for zinc stearate are on its own page, and production routes for all metal stearates are on that page.

2. Fatty acid esters: PETS, montan esters, GMS and stearyl stearate#

Fatty acid esters are the release chemistry of the engineering thermoplastics: pentaerythritol tetrastearate (1202.0 g/mol) survives the 280 to 320 degrees C melt of polycarbonate and blooms to the mold interface without staining the part. PETS, CAS 115-83-3, formula C77H148O8, is a high-molecular-weight polyol ester of stearic acid, low in polarity, so it migrates cleanly rather than hydrolysing at engineering-resin melt temperatures. It carries three active REACH dossiers, is not classified in any of 416 notifications, and Peter Greven holds food contact notification FCN 001963 for saturated pentaerythritol esters.

Montan esters, refined from Gersthofen-process montanic acids and partially esterified with ethylene glycol, 1,3-butanediol or glycerol, have a dropping point of 76 to 105 degrees C and are cleared under 21 CFR 178.3770. Glycerol monostearate and stearyl stearate, CAS 2778-96-3, 537.0 g/mol, round out the class; Peter Greven cites stearyl stearate as its example of a waxy lubricant ester, though its EU food-contact route is not established, so this page names it without an FCM number. The full record of pentaerythritol tetrastearate (PETS) sits on its own page, and montan, complex and polyol esters are compared under ester lubricants.

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

Fatty acid amides do double duty: the same oleamide that gives a polyethylene film its slip at about 0.05 wt% works as a mold release agent above 0.5 wt%, a tenfold difference in level for the same substance. Oleamide, CAS 301-02-0, 281.5 g/mol, melts at 76 degrees C; Struktol's TR 121 bulletin documents both levels side by side. Erucamide, CAS 112-84-5, and the saturated bis-amide ethylene bis stearamide (EBS), CAS 110-30-5, 593.0 g/mol, melting at 135 to 146 degrees C (PubChem) or 138 to 144 (Baerlocher), complete the class; EBS works simultaneously as lubricant, dispersant, release agent and antiblock agent.

Erucamide and EBS are both named directly in 21 CFR 178.3860, but oleamide is not; it appears only in 175.105, for adhesives, and 178.3910, as a metal-rolling lubricant. Struktol TR 251, an EBS-replacement bis-amide blend, is used at 0.5 to 2.0% in ABS, PVC and PS. The full record of oleamide, including the gap in 178.3860, is on its page, and ethylene bis stearamide (EBS) is the bis-amide the FDA names for acetal homopolymer molding, covered later.

4. Waxes: PE wax, oxidised PE wax, montan wax and paraffin#

Waxes release by molecular weight and polarity: polyethylene wax reaches an average molecular mass of up to 10,000 g/mol and sits at the metal interface, while paraffin and Fischer-Tropsch waxes at 200 to 1,000 g/mol are more mobile and more volatile. PE wax, CAS 9002-88-4, carries FCM 549 with no SML; oxidised PE wax, CAS 68441-17-8, carries FCM 811, SML 60 mg/kg, cleared under 21 CFR 177.1620, and is dosed at only 0.07 to 0.3 phr in rigid PVC, the strongest metal-release wax per phr in that Struktol package. Montan wax, CAS 8002-53-7, a crude blend of 62 to 68% esters, 22 to 26% acids and 7 to 15% alcohols and hydrocarbons, melts at 82 to 95 degrees C and carries FCM 529.

A long, non-polar PE-wax chain acts at the metal interface, with little affinity for the polar tool steel, while a polar carboxylate head group, as in oxidised PE wax, gives the same backbone an internal role instead. Refined low-viscosity paraffin, FCM 93, SML 0.05 mg/kg, is restricted from fatty-food contact. Molecular weights and dropping points for all polymer waxes are on that page.

5. Silicones: PDMS oils and silicone masterbatch#

Silicones release by surface energy: a polydimethylsiloxane layer at the part surface has a far lower surface energy than the polymer, which is why silicone works as both an internal masterbatch and an external spray. PDMS, CAS 63148-62-9, forms this low-surface-energy film; EU FCM 575 specifies a molecular weight above 6,800 Da and a viscosity at 25 degrees C of at least 100 cSt. Polyoxyethylene-grafted PDMS, CAS 68937-54-2, is cleared under 21 CFR 177.1520 at no more than 0.3 wt% of the polymer.

Silicone carries a regulatory caution the other classes do not: D4, D5 and D6, tied to silicone manufacture and residues, sit on the REACH Candidate List as PBT or vPvB substances, and Annex XVII entry 70, amended by Regulation (EU) 2024/1328, restricts them to below 0.1% in substances and mixtures from 6 June 2026. Whether a specific professional mold-release spray falls under a derogation is not established here. The carrier polymer's page, polydimethylsiloxane (silicone oil), carries the food-contact specification in full, and entry 70 among the site's REACH Annex XVII restrictions sets the D4, D5 and D6 limits.

Which Mold Release Agent Suits Each Injection-Moulding Polymer?#

The right mold release agent for an injection-molded part is set by the melt temperature, the polymer's polarity and what happens to the part afterwards: high-melting polyol esters for polycarbonate and polyesters, metal soaps and bis-amides for styrenics, montan esters for polyamide, and fatty amides for polyolefins. A release agent should melt below the processing temperature of the polymer but stay well above the mold temperature, or it either fails to bloom to the surface at all or blooms too early and interferes with melt flow.

FDA caps and EFSA intended-use levels are legal maxima or declared levels, not recommended dosages. Supplier ranges come from technical data sheets. Trials decide the final level.

Request quotes for internal mold release additives, specifying polymer, grade or CAS number, volume and any food-contact requirement, with the plastic additive supplier finder. A gated PDF, the Internal Mold Release Selection Chart by Polymer, is available below the table.

Polycarbonate and PC/ABS#

Polycarbonate is the clearest case in the whole family: pentaerythritol tetrastearate is the reference internal release agent for PC, and the US FDA allows it in food-contact polycarbonate at no more than 0.5 wt% of the finished resin, for mold release only. Polycarbonate has a glass transition temperature of 147 degrees C and hydrolyses above 70 degrees C at high humidity, so its release agent has to survive a hot, moisture-sensitive melt without adding extractives beyond the resin's own limit of 0.15 wt%. The 0.5 wt% figure is a legal ceiling, not a recommended level; a molder starts far below it and raises the dosage only if parts still stick. The rest of the PC package, colourants, UV stabilizers and impact modifiers among them, sits on additives for polycarbonate.

ABS, SAN and polystyrene#

ABS, SAN and polystyrene are released with metal soaps and the bis-amide EBS: magnesium stearate at 0.3 to 3 parts in ABS, zinc stearate in polystyrene and EPS, and EBS-type blends at 0.5 to 2.0% across all three. Magnesium stearate does double duty in ABS as both a lubricant and a dusting agent against surface adhesion, and Baerlocher's ZINCUM PS grade line is built specifically for the styrenics. Impact modifiers, antioxidants and colorants for these resins are set out on additives for ABS, SAN and ASA.

Polyamide and PBT#

Polyamide is released with montan esters and metal soaps, because the 260 to 300 degrees C melt of PA66 destroys the lower-melting amides and glycerol esters that work in polyolefins. Struktol TR 063A, an ester blend dosed at 0.2 to 2.0%, is sold against die bearding and drool in PA compounding rather than as a release agent alone, and its performance draws on the same montanic-acid-ester chemistry cleared under 21 CFR 178.3770. That FDA clearance names vinyl chloride plastics specifically, not polyamide, so this page cites 178.3770 as the dropping-point specification source for montan esters rather than as a food-contact clearance for PA parts. Copper heat stabilizers and the rest of the PA package are on additives for nylon (polyamide).

POM (acetal)#

POM is the one molded polymer whose release agent is named in the US food-contact regulation itself: 21 CFR 177.2480 lists ethylene bis stearamide as the lubricant and polyethylene glycol 6000 as the molding assistant for acetal homopolymer. The same regulation caps all stabilizers together at no more than 1.9 wt%, any one substance at no more than 1.0 wt%; POM melts at 175 degrees C on average (homopolymer range 172 to 184). POM is also sensitive to chlorine: 1 to 3 ppm is enough to trigger stress cracking, a reason to check the chloride content of any metal soap used alongside EBS, not a measured failure of any grade. The FDA total-stabilizer caps for acetal are explained in full on additives for POM (acetal).

Polypropylene, polyethylene and other polyolefins#

Polyolefin moldings usually release without help, so the additives that do the job are the ones already in the compound: glycerol monostearate at 0.05 to 0.5% in polypropylene and the fatty amides at more than 0.5% where a part genuinely sticks. Struktol's GMS dosages differ by resin: 0.15% in LDPE, 0.3% in HDPE, 0.05 to 0.5% across polypropylene grades. Calcium and zinc stearate already present at 0.05 to 0.20% as acid scavengers contribute a release effect without being dosed for it separately. One supplier, Kisuma, reports that calcium stearate in PP raffia and BOPP film can form hygroscopic calcium chloride that carries water into downstream processing and can impair metallization; this is a supplier claim, not an independently verified fact. Glycerol monostearate doubles as an antistatic agent in these compounds.

PLA and other bioplastics#

PLA sticks harder than the commodity polyolefins, and 1 wt% calcium stearate is the level at which Tábi and Pölöskei (Budapest University of Technology and Economics, 2021) eliminated stuck and broken parts in injection-molded PLA. Their study, published in Periodica Polytechnica Mechanical Engineering, is the one peer-reviewed dosage figure in our source library for internal release in a bioplastic, and it should not be extended to other bioplastics without a separate trial. Nucleating agents and chain extenders for the same resin are on additives for PLA.

Rigid PVC injection moulding#

Rigid PVC does not get a separate release agent: the lubricant package does the job, with a hydroxyl glycerol ester at 0.7 to 1.5 phr, a complex ester at 0.3 to 0.75 phr, oxidised polyethylene wax at 0.07 to 0.15 phr and calcium stearate at 0.3 to 1.0 phr in an opaque injection-molding compound. External lubricants prolong fusion and can cause haze, exudation and worse printability, weldability and adhesion at high dosage (Baerlocher). Rabinovitch, Lacatus and Summers, in the Journal of Vinyl Technology (1984), argued the internal-versus-external label alone is "deficient in explaining performance" in PVC, since a polar lubricant such as calcium stearate wets the metal preferentially while a non-polar paraffin instead fluidises that layer.

The clear package drops the calcium stearate and the oxidised PE wax entirely, because both cost the compound transparency at the level needed for metal release. The whole internal and external lubricant balance in PVC, not just the release function, is set out under processing lubricants for plastics.

How Much Internal Mold Release Does an Injection-Moulding Compound Need?#

An injection-molding compound needs 0.1 to 3 wt% of lubricant and release additive in total, and the release function on its own usually sits between 0.2 and 1.0 wt%, roughly ten times the level of the same chemistry used as a film slip agent. That total range comes from Hahladakis and colleagues' 2018 review of additive composition in plastic products, cited via Chea and colleagues (2025), bounded by the FDA's 1.0 wt% intended-use level for injection-molded C14-C18 alkanamides (against 0.2 wt% for film, FCM 1065) and by the same oleamide moving from about 0.05% for slip to more than 0.5% for release.

Four factors set where a compound lands inside that range:

• Part geometry and surface area in contact with the cavity, since a deep-draw or textured part needs more release surface than a flat one.
• Melt and mold temperature, which decide whether the additive is mobile enough to migrate to the surface within the cycle.
• The polymer's own polarity, which sets how much additive stays dissolved rather than blooming out.
• Downstream operations, because every wt% at the surface is a wt% a later paint, print or weld step has to work around.

A molder should start at the bottom of the supplier range and raise it only after a trial, since the FDA and EFSA figures above are legal caps, never recommended dosages. A compound at 1.0 wt% of a release additive corresponds to 1.09 PHR (parts per hundred resin) on the resin alone (1.0 divided by the remaining 91.7 wt% of resin, times 100), a unit conversion the PHR to weight percent calculator runs automatically.

How Is Internal Mold Release Dosed: Powder, Pellet or Masterbatch?#

Internal mold release reaches the molding machine in 3 forms: as a powder blended at the compounder, as a dust-free granule or pastille, and as a masterbatch dosed at the hopper, which is the form a molding shop uses when it has no compounding line of its own.

• Powder, blended directly into the resin at the compounding stage, giving direct control over the active level but requiring dust handling.
• Dust-free granule or pastille, from the same metal-soap production routes (precipitation, direct conversion, melt process, continuous COAD) that give neutral-pH, layered particles that dissolve faster.
• Masterbatch, a carrier resin pre-loaded with the additive, typically at 40 to 65 wt% active content (extremes 15 to 80), let down into the base polymer at the machine.

Masterbatch let-down runs from 1 to 5% of the base polymer, so 25 kg per tonne of resin is a 2.5% let-down; the active content in the finished part equals the masterbatch's concentration multiplied by the let-down percentage. A masterbatch holding 20 wt% of a release additive, let down at 2.5% (39 parts base resin to 1 part masterbatch), puts 0.5 wt% of active additive into the part. Accurate ppm-level dosing needs gravimetric loss-in-weight feeders, which is why ppm-level release additives are almost always supplied as masterbatch. Most molding shops add release as a masterbatch rather than as powder, and the let-down ratio calculator works out both forms automatically.

How Do Mold Release Agents Affect Other Additives and Secondary Operations?#

A release agent is a lubricant by another name, so it carries every side effect a lubricant carries: too much of it exudes, hazes a clear part, and makes the surface harder to paint, print or weld. Rabinovitch, Lacatus and Summers made the same point about the internal-versus-external label in 1984: it describes where the additive acts, not how well it performs. Baerlocher's own lubricant performance matrix backs the distinction with data: external lubricants prolong fusion, can cause haziness, can exude at high dosage and could worsen printability, weldability and adhesion, while internal lubricants at a normal dosage do none of these.

Musil and Zatloukal documented a related effect in Ziegler-Natta polyolefin extrusion: the zinc, magnesium or calcium stearates already present as acid acceptors can feed die drool at the extruder head, separate from anything happening inside the mold. Blooming and chalking on a molded part trace back to the same overdosing or low molecular weight that drives release, and the fix is the same: an oligomeric, higher-molecular-weight grade at a lower loading. The full map of synergy and antagonism across every additive family is covered under additive interactions.

Which Mold Release Agents Are Allowed in Food-Contact Injection Moulding?#

Food-contact injection moldings may contain only release agents that appear on the EU Union list in Regulation (EU) No 10/2011, within their specific migration limit, or in the relevant US section of 21 CFR, within its weight limit, and the two systems set those limits in different units. No substance on this page is described as "FDA approved"; the correct language is "listed", "authorised" or "cleared under" the specific 21 CFR section, because an approval in the everyday sense does not exist in either system.

EU 10/2011: FCM numbers, metal SMLs and the stearate route#

The metal stearates illustrate how the EU handles release agents: zinc, calcium and magnesium stearate carry no FCM number of their own, because Article 6(3)(a) covers them as salts of the authorised stearic acid (FCM 106), and the limit that actually bites is the Annex II metal SML of 5 mg/kg for zinc. That 5 mg/kg zinc limit has applied since Regulation (EU) 2020/1245. Calcium and magnesium carry no Annex II metal SML at all, which is one reason they are the default choice in food-contact compounds where zinc's own limit would otherwise constrain the dosage.

US limits are maximum use levels, not recommended dosages. EU entries carry the overall migration limit of 10 mg/dm2 and, where no specific SML is listed, the generic 60 mg/kg.

US limits: 21 CFR 177.1580, 178.3860 and 178.3770#

The US regulates release agents in three places: 21 CFR 177.1580 for pentaerythritol tetrastearate in polycarbonate, 21 CFR 178.3860 for the amide and wax release agents used in any polymer, and 21 CFR 178.3770 for the montan esters used as PVC lubricants. Section 178.3860 is titled "release agents" outright and names erucamide, oleyl palmitamide, stearyl erucamide and saturated fatty acid amides, plus rice bran wax at no more than 1.0% for dry foods; it is the section a molder cites for the amide classes, which is why the oleamide gap matters so much. Section 177.2480 adds a fourth, narrower clearance for POM homopolymer, naming EBS as the lubricant and PEG 6000 as the molding assistant. The structure of these 21 CFR parts is decoded in full on FDA food contact rules.

Medical, toy and drinking-water mouldings#

Medical, toy and drinking-water moldings add a second layer of rules on top of food contact, and the release agent has to clear both. Zinc and calcium stearate both carry favourable classification profiles: calcium stearate is not classified in 85.5% of 3,808 GHS notifications, and zinc stearate in 61.3% of 2,108. Neither figure is a medical-device or toy clearance, and no positive-list entry here names a release agent for medical, toy or drinking-water moldings specifically, so a molder in those applications checks the relevant sector standard rather than the food-contact table above. Sterilization and biocompatibility constraints for the medical case are on additives for medical plastics.

Who Supplies Mold Release Agents for Injection Molding?#

Internal mold release agents come from a small group of specialist lubricant producers, and the same chemistry is sold under several brand names. Baerlocher, based near Munich, has been family-owned for more than 200 years, employs 1,150 people, and sells its metal soaps and lubricants as CEASIT, ZINCUM and BAEROLUB. Peter Greven sells the same categories as LIGASTAR, LIGALUB and LIGASTAB, and holds food contact notification FCN 001963 for saturated pentaerythritol esters. Struktol, of Stow, Ohio, supplies the metal-stearate and blended grades named throughout this page, from TR 121 (oleamide) to TR 251 (the EBS replacement) and V-HRW (the PVC ester package).

This table lists producers and brand lines only; it is not a performance-equivalence claim between grades. Buyers should compare grades by CAS number, metal content and food-contact route rather than by brand name alone. Plants and grades by company are catalogued in the directory of calcium and zinc stearate manufacturers. Request quotes for internal mold release additives, specifying polymer, grade or CAS number, volume and any food-contact requirement, through the plastic additive supplier finder.

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What Else Does an Injection Moulder Check Before Adding a Release Agent?#

A release agent is the last additive a molder adds and the first one to suspect when a surface goes wrong, because the compound already carries lubricants, acid scavengers and slip additives that do part of the same job. Before adding a dedicated release grade, it is worth totalling the release contribution already present from acid scavengers, since a stearate added for one function often does part of the other's job for free. The full package a molder specifies for a shot is set out on additives for injection molding.

Mold release in other moulding processes#

Compression and transfer molding of SMC and BMC use the same metal soaps at higher levels, with zinc stearate preferred because it melts lower than calcium stearate and precipitated grades releasing best because of their fineness. Baerlocher's ZINCUM SW 1626 and Peter Greven's CEASIT SW 1725 are examples of the fine, precipitated grades sold for this use, and the same particle-size trade-off documented for injection molding applies here too. Internal release for polyurethane and RIM molding is not established in our source library, so this page names no mechanism and no level for that process. SMC, BMC and fiberglass practice is covered under mold release agents for composites, and polyurethane and RIM are handled separately under mold release agents for polyurethane.

Can WD-40 or Vaseline be used as a mold release?#

No: WD-40 and petroleum jelly are not mold release agents for injection molding, because neither is a listed food-contact substance, neither survives a 200 to 320 degrees C melt, and both contaminate the tool and the part surface. Our source library holds no performance data on either product, so this answer rests on the scope rule and the temperature argument alone.

Does mold release affect painting, printing and welding?#

Yes, at the wrong level: an external release film sits on the part surface and can worsen printability, weldability and adhesion, while an internal lubricant at a normal level does not. That distinction comes from Baerlocher's own lubricant performance comparison. Whether silicone contamination specifically causes paint craters or fisheyes is not established here, so this answer states only the general internal-versus-external finding.

Is zinc stearate safe to use as a mold release agent?#

Zinc stearate carries no EU harmonised hazard classification, and 61.3% of the 2,108 notifications in ECHA's classification inventory report it as not classified, with a minority notifying aquatic hazards H400 and H413 and respiratory irritation H335. The FDA lists it as GRAS under 21 CFR 182.8994, and the EU sets its Annex II zinc migration limit at 5 mg/kg. The aquatic-hazard minority matters most for a zinc stearate masterbatch's safety data sheet.

What is a semi-permanent mold release agent?#

A semi-permanent mold release agent is an external coating that bonds to a clean tool surface and gives several releases per application, unlike a sacrificial coating that is reapplied before every cycle. It belongs to the external, process-chemical side of this topic rather than the internal additive side covered in the main sections above.

Release agents outside plastics moulding#

Release agents for concrete, plaster, baking tins, die casting and asphalt share the name and almost nothing else, and this reference covers only release agents used to mold plastics. A bare search for "mold release agent" returns all of these uses mixed together, which is why this page deliberately excludes concrete form release, plaster casting, bakery release, die casting release and asphalt release: none shares a chemistry, a dosage or a regulation with the additives covered here.

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