Silicone Mold Release Agents: 5 Types, Use and D4/D5/D6 Compliance

Silicone mold release agents are polydimethylsiloxane-based products that put a low-surface-energy siloxane film between a moulded plastic part and the tool, and they are supplied in 5 forms: neat silicone oils, water-based emulsions, solvent-based and dry-mist sprays, semi-permanent reactive coatings, and silicone additives compounded into the polymer itself. Four of those 5 forms are applied to the mould and are process chemicals; only the fifth is a plastics additive, and that difference decides which rules apply to it. So which form suits which process, and what changed in the EU on 6 June 2026?

Silicones are one of the four classes that Ullmann's Encyclopedia of Industrial Chemistry names for release agents, alongside waxes, fatty esters and metallic soaps (Lammerting, 2000), which makes them one branch of a much wider group of plastic additives. The active chemistry in almost every one is polydimethylsiloxane, CAS 63148-62-9, whose silicon-oxygen backbone is thermally stable and unreactive towards the polymer it releases.

This page defines a silicone mold release agent and names the silicone chemistries used in one, explains why a siloxane film releases a part and how long that film survives, sets out the 5 product types in durability order, matches each type to the moulding process that uses it, gives every sourced quantity with the instrument behind it, states where silicone is the wrong choice, lists the proxy methods that stand in for the release-force standard that does not exist, works through the 3 regulatory routes, and names the two supply chains a buyer deals with.

Key figures

• 5 product types of silicone release agent: 4 applied to the tool, 1 compounded into the polymer
• 0.1 % by weight: the D4, D5 and D6 limit in substances and mixtures on the EU market since 6 June 2026 (REACH Annex XVII entry 70, Regulation (EU) 2024/1328)
• 0.3 wt% of the polymer: the FDA maximum use level for polyoxyethylene-grafted PDMS as a non-fluorinated extrusion aid (21 CFR 177.1520)
• Mw above 6,800 Da and viscosity at 25 °C of at least 100 cSt: the EU specification attached to PDMS as FCM 575 (Regulation (EU) No 10/2011)

What Is a Silicone Mold Release Agent?#

A silicone mold release agent is a release agent whose active chemistry is a siloxane polymer, most often polydimethylsiloxane, and it is used to stop a plastic or composite part from bonding to the tool it is formed in. The same product is also called a mould release agent, a parting agent or simply a release agent, and Murphy's Additives for Plastics Handbook, 2nd edition, treats release agents in one chapter together with lubricants, slip and antiblock additives.

Silicone is one branch of a wider taxonomy of mold release agents for plastics, cut by chemistry rather than by product form. The silicone branch is one of the 6 types on the parent page for mold release agents for plastics, which compares it with metal soaps, esters, amides, waxes and the external systems.

Which silicone chemistry is used: PDMS, silicone resins and modified siloxanes#

The silicone used in release agents is polydimethylsiloxane (PDMS, CAS 63148-62-9, EC 687-578-3), a linear siloxane polymer sold as silicone oil or dimethicone, and two modified forms appear alongside it: polyoxyethylene-grafted PDMS (CAS 68937-54-2), which is water-dispersible, and crosslinked silicone resins such as methylsilsesquioxane (CAS 68554-70-1, EC 614-610-5), which are solid particles rather than fluids. The empirical formula of PDMS is written (C2H6OSi)n, and its trade synonyms are silicone oil, dimethicone and dimethylpolysiloxane.

Polydimethylsiloxane does 4 separate jobs in plastics processing, and only the first two of them are release jobs.

• External mold release, as a neat oil or a water-based emulsion applied to the tool.
• Slip and lubricant additive, supplied as a silicone masterbatch and compounded into the polymer.
• Base chemistry of silicone-type PFAS-free processing aids, in the polyether-grafted form.
• Matrix of solid silicone-resin particles, used as an antiblock and a light diffuser in film.

Polydimethylsiloxane is a polymer, and polymers are exempt from registration under Article 2(9) of Regulation (EC) No 1907/2006, which is why no REACH registration dossier exists for the silicone itself and why the regulated species in a silicone release agent are its small-molecule residues. Full identity, grades and the complete regulatory matrix for polydimethylsiloxane (silicone oil) sit on its own substance page.

Internal silicone release versus external silicone release#

The two routes are not interchangeable: an external silicone release agent is sprayed, wiped or flooded onto the tool and is a process chemical, while an internal silicone release agent is compounded into the polymer and migrates to the part surface, which makes it a plastics additive with its own food-contact clearances. External products reach the tool in one of three carriers, water, solvent or a co-solvent blend, while the internal route reaches the melt in the carrier resin of a masterbatch.

Table 1. The two silicone release routes and the law that governs each

The compounded route across all chemistries, not only silicone, is covered under internal mold release agents, which sets out the metal soaps, esters, amides and waxes that compete with a silicone masterbatch inside the same formulation.

Is a silicone mold release agent a plastics additive?#

Only sometimes: a silicone release agent compounded into the polymer is a plastics additive, while a silicone spray or emulsion applied to the tool is a process chemical, and the two are governed by different legislation. This reference covers external silicone release because it is used to mould plastics, in injection moulding, polyurethane and reaction injection moulding, composites, rotational moulding and thermoforming. Release agents for concrete forms, plaster, bakery use, die casting and asphalt share the head term and fall outside a reference that covers additives for plastics only.

How Do Silicone Mold Release Agents Work?#

Silicone mold release agents work by occupying the interface: the siloxane film has a lower surface energy than either the tool steel or the cooling polymer, so the part adheres to the film instead of to the mould and leaves with a lower ejection force. The film reaches that interface from one of two directions, from the tool or from inside the melt; but how long does it survive there?

Why a siloxane film releases a moulded part#

A siloxane film releases a part because the silicon-oxygen backbone of polydimethylsiloxane presents methyl groups outward, giving a non-polar, low-surface-energy surface that neither tool steel nor a cooling thermoplastic wets well. That same backbone is thermally stable and unreactive towards the polymer, so the film survives the melt temperature without decomposing into the part and without bonding to it.

The direction of supply changes how the film is maintained, not how it works. An external film is renewed from outside, by reapplication between cycles or by a bonded coating that lasts across them, while an internal one is renewed by continued migration of the additive out of the compound, the same transport mechanism that governs additive migration in plastics for every additive class. Both leave silicone at the part surface, which is why the choice has consequences after moulding.

How long the film lasts: sacrificial versus semi-permanent#

Release agents divide into 2 durability classes: a sacrificial coating is applied before every moulding cycle, while a semi-permanent agent bonds to a clean mould surface and gives multiple releases per application. That distinction is the operational difference a specifier is choosing between, because it sets how often production stops to renew the film.

• Sacrificial coatings: applied before every moulding cycle, with the film consumed or carried away by each part, which makes the application step part of the cycle time.
• Semi-permanent agents: bonded to a clean mould surface, not reapplied every cycle, and giving multiple releases per application, which moves the application step into tool preparation.

No cycle count per application is published in this reference: the sourced wording goes no further than multiple releases per application, and the figures quoted in product literature are claims with no method attached.

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

The 5 types of silicone mold release agent are neat silicone oils, water-based silicone emulsions, solvent-based and dry-mist sprays, semi-permanent reactive silane and siloxane coatings, and internal silicone additives compounded into the polymer; the first four are applied to the tool and the fifth is applied to the plastic. Table 2 lists them in durability order, from the single-cycle fluid to the bonded coating that gives multiple releases per application, and then the one route that does not touch the tool.

Table 2. The 5 types of silicone mold release agent

Carriers and process columns follow the family taxonomy used across this site. No cycle counts, dilution ratios or viscosities are given, because this reference holds none; ask the supplier for the technical data sheet and the cyclosiloxane declaration.

1. Silicone oils: neat polydimethylsiloxane fluids#

Neat silicone oil is undiluted polydimethylsiloxane applied directly to the tool, and it is also the base fluid from which the emulsions and sprays in types 2 and 3 are made. As a product form it is the simplest of the five, with no carrier to flash off and nothing to cure.

One numeric anchor exists for the fluid itself, and it belongs to a food-contact specification rather than to a product range. Where the same chemistry is used as an additive inside a food-contact plastic instead of on the tool, Regulation (EU) No 10/2011 authorises polydimethylsiloxane as FCM 575 (Ref 76721) only above a molecular weight of 6,800 Da and at a viscosity at 25 °C of at least 100 cSt. That 100 cSt figure is a regulatory minimum for an authorised additive, not a recommended viscosity grade for a release fluid, and this reference holds no viscosity range for release-grade silicone oils.

2. Water-based silicone emulsions#

Water-based silicone emulsions are polydimethylsiloxane dispersed in water, which takes the solvent out of the carrier and leaves water to flash off the hot tool before the next shot. Water is one of the three carriers used for external release products, alongside solvent and co-solvent systems, and it is the carrier most often specified for polyurethane and reaction injection moulding, where wax and silicone emulsions are the established external route.

The chemistry that makes a siloxane disperse in water is a graft rather than a surfactant alone: polyoxyethylene-grafted PDMS (CAS 68937-54-2) is the water-dispersible modified form, and the FDA clears it for olefin polymers at up to 0.3 wt% of the polymer as a non-fluorinated extrusion aid under 21 CFR 177.1520. That clearance applies to the grafted siloxane used in the polymer and not to an emulsion sprayed on a tool. The same grafted siloxane chemistry is the leading non-fluorinated option among PFAS-free processing aids, where it does a flow job rather than a release job.

3. Solvent-based and dry-mist silicone sprays#

Solvent-based and dry-mist sprays carry polydimethylsiloxane in a volatile carrier that flashes off and leaves the siloxane film behind, which makes them the fastest form to apply and the most common sacrificial form. A spray is renewed before each cycle rather than bonded to the tool, so it belongs to the sacrificial class and its film lasts one part.

This is also the form most clearly caught by the EU restriction, because a spray is a mixture. Since 6 June 2026, D4, D5 and D6 may not be placed on the EU market in substances or mixtures at a concentration of 0.1 % by weight or more, under REACH Annex XVII entry 70 as amended by Regulation (EU) 2024/1328. The derogation tiers that qualify that limit, and the declaration a buyer needs from the supplier, are set out under the regulatory heading below. Spray distance, coat weight and flash-off time are not published here: no value for any of the three is held in this reference.

4. Semi-permanent reactive silane and siloxane coatings#

Semi-permanent coatings are reactive silane or siloxane systems that bond chemically to a clean mould surface instead of sitting on it, so one application releases more than one part. They are supplied in the same three carriers as the sacrificial forms, water, solvent and co-solvent, and the chemistry rather than the carrier is what separates them.

The bond needs a clean tool, which makes applying one a tool-preparation decision rather than a shot-by-shot decision. That is why the cycle economics favour semi-permanent coatings wherever a tool runs a long series between cleanings, and semi-permanent release coatings dominate in epoxy and fiberglass moulding for exactly that reason. Epoxy, unsaturated polyester, SMC and BMC practice is covered under mold release agents for composites. No cure schedule, bake temperature or number of releases is given here: multiple releases per application is the sourced wording and the ceiling of what this reference states.

5. Internal silicone additives: masterbatch and polyether-grafted siloxanes#

Internal silicone additives are silicone masterbatches and polyether-grafted siloxanes compounded into the polymer, where they migrate to the part surface and release it from the inside, without anything being applied to the tool. This is the only one of the 5 types that is a plastics additive in the sense this reference uses, and it is therefore the only one with an additive clearance behind it.

The number attached to it is a legal ceiling: the FDA clears polyoxyethylene-grafted PDMS for olefin polymers at up to 0.3 wt% of the polymer as an extrusion aid under 21 CFR 177.1520, and the EU authorises polydimethylsiloxane as FCM 575 above 6,800 Da. Most silicone additives reach the compound as an additive masterbatch rather than as a neat fluid, and no let-down ratio for a silicone release masterbatch is published in this reference.

The same siloxane chemistry is sold for 3 further jobs besides release, which is why the release function is rarely bought on its own: slip in film, wear and friction reduction in the part, and flow improvement as a non-fluorinated processing aid. Silicone also appears among the tribological additives that reduce wear and friction in moulded parts. Methylsilsesquioxane, the solid silicone-resin form, is an antiblock, slip and light-diffuser additive rather than a release agent. No commercial silicone masterbatch or grafted-siloxane trade line is named here, because the market references for them are unverified against supplier data sheets.

Which Plastics and Moulding Processes Use Silicone Release?#

Silicone release is used in 5 plastics processes, and the form follows the process: emulsions and sprays in thermoplastic injection moulding, emulsions in polyurethane and RIM, semi-permanent coatings in composites, and sprays or emulsions in rotational moulding and thermoforming. Table 3 sets each process against the non-silicone internal additive it competes with, and in two of them that non-silicone route is the one with a published limit.

Table 3. Process matrix: silicone route, non-silicone route and the sourced number

Every FDA figure in this table is a legal maximum use level, not a recommended dosage. Trials on the tool set the working level.

Injection moulding of thermoplastics#

Thermoplastic injection moulders use silicone release in two ways: an emulsion or spray on the cavity between shots, which is a process decision, or a silicone masterbatch in the compound, which is a formulation decision taken once. The two differ in where cost and control sit: a sprayed film is renewed inside the cycle, a compounded additive is specified before the material is bought. Release selection by polymer, for every chemistry and not only silicone, is set out under mold release agents for injection molding.

The comparison that matters commercially appears in food-contact mouldings. Where the part is a food-contact polycarbonate moulding, the established internal route is not silicone but pentaerythritol tetrastearate, which the FDA clears for mold release use at up to 0.5 wt% of the finished resin under 21 CFR 177.1580, and silicone carries no equivalent per-polymer release limit in that section. The PETS route and the rest of the polycarbonate package are covered under additives for polycarbonate.

Polyurethane, RIM and integral-skin foam#

Polyurethane and reaction injection moulding are external-release processes in practice: wax and silicone emulsions are applied to the tool, because a reacting system leaves little room for an additive compounded in advance. Integral-skin foam follows the same pattern, since the skin forms against the tool surface that the release film protects.

An internal release route for polyurethane exists in the patent literature, and the classic version compatibilises a metal soap in the polyol side, but no primary source for it has been retrieved into this reference, so no chemistry and no level is published here yet. The polyurethane case is treated on its own page, mold release agents for polyurethane.

Composites: epoxy, unsaturated polyester, SMC and BMC#

Composite moulders are the main users of semi-permanent silicone coatings, because an epoxy or unsaturated-polyester tool runs a long series of parts between cleanings and a sacrificial film has to be renewed on every one. Hand lay-up, SMC and BMC share that economics, and the sacrificial alternative in the same shops is a wax rather than a silicone.

The internal comparison in thermoset compounds is a metal soap. In SMC and BMC the preferred internal release agent is zinc stearate, chosen for its lower melting point, and precipitated grades release best because of their fineness (Peter Greven plastics brochure, 09/2025). Grades, particle form and the regulatory status of zinc stearate are on its substance page.

Rotational moulding and thermoforming#

Rotational moulding and thermoforming use sprays and emulsions on the tool, because both form the part against a surface that is reheated every cycle and neither compounds an additive for release alone. Both sit inside the external-release scope this reference covers and draw on the same three carriers as the other external forms. No rotomoulding or thermoforming release level is held here, so no figure is given.

How Much Silicone Release Agent Is Used?#

The only sourced number for a silicone release additive is a legal ceiling and not a dosage: the FDA clears polyoxyethylene-grafted PDMS for olefin polymers at up to 0.3 wt% of the polymer as an extrusion aid under 21 CFR 177.1520. For the external forms there is no published use level at all, because the quantity on the tool is a coat weight set by the spray or wipe method rather than a percentage of anything, and no coat-weight data for silicone release agents is held in this reference.

Table 4. What the numbers on this page actually are

Rows 1, 5 and 6 are maximum permitted or measured levels, not recommendations. Rows 3 and 4 limit an impurity in the product you buy, not a dosage you add.

Five questions set the level, and they should be answered in this order.

1. Decide whether silicone can go into the compound at all, or whether only an external product is possible.
2. Decide whether the tool runs long enough between cleanings to justify a semi-permanent coating instead of a sacrificial film.
3. Check what happens to the part surface afterwards, because painting, printing, plating and bonding all react to residual silicone.
4. Check the food-contact and cyclosiloxane positions in every market the part is sold into.
5. Set the lowest level that releases, confirm it on the tool, and watch the part surface and the tool for build-up.

Converting a masterbatch addition rate into a percentage in the part is arithmetic the let-down ratio calculator does, and it is the step where a ceiling such as 0.3 wt% of the polymer is checked against the addition rate rather than against the masterbatch concentration.

Cost per kilogram of compound at a given addition rate is handled by the additive dosage and cost-in-use calculator, which is the comparison that decides between an internal masterbatch and an external product, since the external route carries a labour cost inside the cycle that no percentage captures.

When Silicone Mold Release Is the Wrong Choice#

Silicone release is the wrong choice whenever the part surface has to accept something else afterwards, because the same film that releases the part stays on it. That is a predictable consequence of the mechanism, not a product defect; so which operations are affected, and what replaces silicone when they are?

Painting, printing, plating and bonding after moulding#

Four secondary operations are sensitive to residual silicone: painting, printing, metallising or plating, and adhesive bonding, because all four need a surface that a liquid wets and a low-surface-energy siloxane film is designed not to be wetted. The internal route makes that persistent, since a compounded additive keeps migrating to the surface for as long as the part is in service.

• Painting: the paint has to wet the substrate before it levels and cures, and a siloxane film resists that wetting.
• Printing: pad printing transfers a thin ink film that needs the same wetting over a smaller area.
• Metallising or plating: deposition and its primer layers depend on surface condition, not on bulk polymer properties.
• Adhesive bonding: the adhesive bonds at the interface where the release film sits, as do ultrasonic and solvent welding.

This reference holds no measured adhesion or bond-strength data for silicone-contaminated plastic surfaces, so the page states the mechanism and the decision rule and gives no figures; grades sold as suitable for painting or bonding should be qualified on the real part before a line commits to them. Surface defects traced back to a release agent are diagnosed under troubleshooting additive-related defects.

Silicone transfer, build-up and mould cleaning#

Silicone that is reapplied every cycle and not fully carried away by the part accumulates on the tool, which is why cleaning is part of a silicone release system rather than a separate maintenance task. Accumulation is the documented consequence of a sacrificial film, and it shows where the tool is hardest to wipe: the vents and the textured areas of the cavity.

A semi-permanent coating makes that cleaning step explicit, because it has to bond to a clean mould surface. The tool is therefore stripped before it is recoated, and a shop that has been running sacrificial silicone cannot switch to a semi-permanent system without that step. No build-up rate, cleaning interval or cleaning chemistry is published here. This accumulation is not plate-out: plate-out in PVC processing is the PVC-specific deposit of formulation components on calender rolls, dies and screws, it is driven by over-lubrication and incompatible external lubricants, and it is a different mechanism with its own page.

Silicone-free release agents for plastics#

The silicone-free routes with published limits are the ester, metal-soap, fatty-amide and wax classes: pentaerythritol tetrastearate at up to 0.5 wt% in food-contact polycarbonate, zinc stearate in SMC and BMC, the fatty amides listed by name in 21 CFR 178.3860, and rice bran wax at up to 1.0 % for dry foods. Fluoroelastomer, used as a processing aid rather than as a release agent, is the other alternative chemistry this reference records against polydimethylsiloxane.

• Esters: pentaerythritol tetrastearate, cleared at up to 0.5 wt% of the finished resin in food-contact polycarbonate under 21 CFR 177.1580, for mold release use only.
• Metal soaps: zinc and calcium stearate, with zinc stearate preferred in SMC and BMC for its lower melting point and calcium stearate measured at 1 wt% as a PLA demolding agent by Tábi and Pölöskei (2021, Periodica Polytechnica Mechanical Engineering).
• Amides and waxes: erucamide, oleyl palmitamide, stearyl erucamide and saturated fatty acid amides listed in 21 CFR 178.3860, oleamide above 0.5 % for release (Struktol TR 121), rice bran wax at up to 1.0 % by weight for dry foods, and N,N-dioleoylethylenediamine at up to 0.055 mg per square inch in PVC films.

Ester release chemistry, including pentaerythritol tetrastearate (PETS), is covered on its own substance page.

The soap route across PVC, styrenics and thermosets is on metal stearates, where the zinc and calcium grades above are compared on melting point and particle form.

How Is Silicone Release Performance Tested?#

No release-force or demolding-force standard is held in this reference, so silicone release is verified on the tool and then checked by proxy methods: coefficient of friction to ASTM D1894-24 or ISO 8295, blocking to ASTM D3354-21, additive content by extraction and liquid chromatography, and migration by the food-contact methods. Naming that gap is the honest answer, and it is also the one no supplier page gives: performance claims on this product category are made without a method behind them.

Table 5. Proxy methods, because no release-force standard is held here

The timing caveat applies directly to the internal route. A migrating additive blooms to the surface over days, so a friction or blocking result depends on how long after production the specimen was measured, and two laboratories can report different values on the same compound without either being wrong. Method detail, specimen conditioning and that time dependence are on coefficient of friction and blocking of plastic film.

Content and migration answer different questions from friction: extraction with liquid chromatography measures what is in the compound, at a limit of detection of about 2 ppm, while a migration test measures what leaves the article. Food-contact migration testing under EU 10/2011, EN 1186 and EN 13130 is covered on migration testing of plastics for food contact.

Which Rules Apply to Silicone Mold Release Agents?#

Silicone mold release agents are governed by 3 routes: the REACH Annex XVII entry 70 restriction on the cyclosiloxanes D4, D5 and D6 in the product you buy, the EU and US food-contact clearances that apply to silicone inside the plastic, and the general REACH and CLP duties of the mixture itself. Polydimethylsiloxane is a polymer and is exempt from REACH registration as one under Article 2(9) of Regulation (EC) No 1907/2006, which is why the regulated species in a silicone release agent are its small-molecule residues and not the silicone.

D4, D5 and D6: REACH Annex XVII entry 70 since 6 June 2026#

Since 6 June 2026, the cyclosiloxanes D4, D5 and D6 may not be placed on the EU market in substances or mixtures at a concentration of 0.1 % by weight or more, under REACH Annex XVII entry 70 as amended by Regulation (EU) 2024/1328, and a silicone mold release spray or emulsion is a mixture. Two later dates sit in the same entry: leave-on cosmetics follow from 6 June 2027 and medical devices and medicinal products from 6 June 2031. The restriction sits alongside the other additive-relevant entries listed under REACH Annex XVII restrictions on plastic additives.

Table 6. D4, D5 and D6: identity and regulatory status

None of the three has a page on this site: they are residues of silicone manufacture and substances of concern, not plastics additives. They are covered here because they decide what a silicone release agent may contain.

The derogations are tiers rather than a blanket exemption. Industrial uses are derogated, covering use as a monomer, as an intermediate, in formulation, in the production of articles and in non-metal surface treatment, and specific residue levels are allowed 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 up to 0.2 % for devices. It is not established how a professional mold-release spray or emulsion is classed against those categories, so the cyclosiloxane content is a figure to require from the supplier in writing rather than to assume.

Two statements about entry 70 need separating, and the second is the one that gets misread.

• What entry 70 limits: the residual D4, D5 and D6 content of the product placed on the market, at 0.1 % by weight, with the later dates for leave-on cosmetics (6 June 2027) and for medical devices and medicinal products (6 June 2031).
• What entry 70 does not do: it does not ban silicone release agents, it does not restrict polydimethylsiloxane itself, and it sets no limit on how much release agent is applied to a tool.

Cyclosiloxanes are residues of silicone manufacture rather than deliberate additives, which is why the restriction reads as a purity specification on the product a moulder buys. The duties that attach to a restricted substance and to a mixture are explained under REACH and plastic additives.

Are D4, D5 and D6 on the SVHC Candidate List?#

Yes: D4, D5 and D6 were all added to the REACH Candidate List on 27 June 2018, as persistent, bioaccumulative and toxic substances under Article 57(d) and as very persistent and very bioaccumulative substances under Article 57(e). None of the three is on Annex XIV, so no authorisation is required for their use, and what applies to them is the Annex XVII entry 70 restriction plus the Candidate List communication duties. All plastic-additive entries on the list, with their inclusion dates, are tracked on the SVHC Candidate List, which holds 253 entries as of its 4 February 2026 update.

What PBT and vPvB substances means, and why a vPvB listing is not an Annex XIV authorisation requirement, is defined in the glossary.

Food-contact use: EU 10/2011 FCM 575 and 21 CFR 177.1520#

In the EU, polydimethylsiloxane is authorised as a food-contact plastics additive under FCM 575 of Regulation (EU) No 10/2011, provided its molecular weight is above 6,800 Da and its viscosity at 25 °C is at least 100 cSt; in the US, polyoxyethylene-grafted PDMS is cleared as an extrusion aid for olefin polymers at up to 0.3 wt% of the polymer under 21 CFR 177.1520; and neither of those is a clearance for a silicone release agent sprayed on the tool. How specific and overall migration limits work alongside an FCM listing is explained on EU 10/2011, whose generic specific migration limit is 60 mg/kg and whose overall migration limit is 10 mg/dm2.

Table 7. Regulatory matrix for the silicone species on this page

Blank and absent entries are stated as absences, not as approvals. Never read a missing entry as a clearance.

Both clearances above apply to silicone inside the plastic. This reference holds no authorisation route for an external silicone release agent used as a process chemical on a food-contact article, and the FDA's own release-agent section, 21 CFR 178.3860, lists fatty amides and waxes rather than silicones. A food-grade or food-safe claim on a release spray should therefore be backed by the supplier naming the section it relies on, and the generic EU limits still apply to whatever ends up on the article, at an overall migration limit of 10 mg/dm2 and a generic specific migration limit of 60 mg/kg. A grade-by-grade status check across REACH, the FDA and EU 10/2011 is what the additive regulatory status checker is for.

Drinking water, packaging PFAS rules and bisphenols in silicones#

Three further instruments touch silicone in plastics processing: the EU drinking-water positive list, the packaging PFAS limits of the PPWR, and the EU bisphenol prohibition, which names silicones among the food-contact materials it covers. Methylsilsesquioxane holds EU drinking-water positive list entry 0639 under Implementing Decision (EU) 2024/367, and positive-list entries alongside the NSF/ANSI 61 and KTW routes are compared on plastic additives in drinking-water contact.

The packaging rules are the reason silicone demand in processing is rising rather than falling. From 12 August 2026, Article 5(5) of Regulation (EU) 2025/40 bars food-contact packaging containing 25 ppb or more of any targeted PFAS, 250 ppb or more of the sum of targeted PFAS, or 50 ppm or more of total PFAS including polymeric PFAS, and silicone and polyether-siloxane chemistry is one of the PFAS-free routes that replaces fluoropolymer processing aids, reviewed as such by Donahue-Boyle and co-workers (2026, RSC Sustainability). Those packaging limits and their measurement questions are on the PPWR page.

Regulation (EU) 2024/3190 prohibits BPA and other hazardous bisphenols and their derivatives in food-contact materials, and names silicones explicitly in that scope alongside plastics, adhesives, rubbers, inks, varnishes and coatings; it has been in force since 20 January 2025. The prohibition and what it covers are on bisphenols in plastics.

Who Supplies Silicone Mold Release Agents?#

Silicone release agents come from two different supply chains: the silicone producers that make the fluids and the resins, and the release-agent formulators that turn them into emulsions, sprays and semi-permanent coatings. Evonik, Momentive, Dow, Shin-Etsu and Wacker appear in this reference as producers of silicone and organofunctional silane chemistry rather than as documented release-agent brands. The release-agent formulators have no record here, and no supplier category for release agents exists on this site yet, so no ranking is presented that cannot be supported. Company-by-company portfolios across all additive families are indexed in the plastic additive manufacturers and suppliers directory.

Buyers should compare silicone release agents on three things the label rarely shows: the CAS number of the active siloxane, the carrier, and a written declaration of the D4, D5 and D6 content against the 0.1 % limit of REACH Annex XVII entry 70. No market size, growth rate or price is published for this family, because none is held in this reference.

Trade names and their CAS equivalents can be resolved with the plastic additive trade name lookup, which is the practical first step when a data sheet names a product rather than a chemistry.

What Do Moulders Use Instead of Silicone Release?#

A moulder choosing against silicone has two directions to look: the other release-agent classes, which are waxes, fatty esters, fatty amides and metallic soaps, and the other jobs silicone itself does in plastics, where release is a side effect rather than the purpose. Both directions lead back to the same family taxonomy, cut once by chemistry and once by function. The complete comparison of all 6 types, including the external systems, is on mold release agents for plastics and composites.

Non-silicone release agents for plastics and composites#

The non-silicone classes split by chemistry: ester release agents such as pentaerythritol tetrastearate, metal soaps such as zinc and calcium stearate, fatty amides such as oleamide, and waxes including the montan esters. Each carries a published limit or use level that silicone lacks for the same job: 0.5 wt% in food-contact polycarbonate for PETS, above 0.5 % for oleamide, and 1.0 % by weight for rice bran wax in dry-food applications under 21 CFR 178.3860.

Wax chemistry across PE, oxidised PE, Fischer-Tropsch and montan grades is on polymer waxes, where the montan esters used for release are specified.

Release agents for silicone rubber moulding, die casting, concrete, plaster and bakery use share the head term and fall outside a reference that covers additives for plastics only. Where a release agent is also a lubricant, the overlap is mapped on processing lubricants for plastics.

Silicone's other jobs in plastics: slip, antiblock and processing aid#

Silicone earns its place in plastics for 3 jobs besides release: slip in film, antiblock and light diffusion as solid silicone-resin microspheres, and flow improvement as a non-fluorinated processing aid. The film-slip use of silicone is covered on silicone slip additives, where the same polydimethylsiloxane chemistry is dosed for surface friction rather than for demoulding.

Methylsilsesquioxane microspheres are the solid silicone-resin form, used for antiblock and light diffusion rather than release: the grade recorded here has a refractive index of 1.42 and is supplied in particle sizes of 1.8 to 2.3, 2.3 to 3.1, 4.0 to 5.0 and 8.5 to 10.5 µm.

The processing-aid job is the one that is growing. Why the industry is moving to silicone and other non-fluorinated chemistries is set out under PFAS in plastics, which covers the fluoropolymer processing aids that the polyether-grafted siloxanes replace.

Do you need a release agent for silicone moulds?#

Usually not: a silicone mould is already a low-surface-energy surface, which is the property a release agent is there to provide, so the question only arises when silicone is cast against silicone or when a cast resin bonds chemically to it. This page covers silicone release agents used to mould plastics, not products used with a silicone mould. Casting and resin-moulding release, including the mould-side question, is covered under release agents for composite moulding.

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

This reference holds no data on petroleum jelly, aerosol lubricant sprays, cooking sprays or poly(vinyl alcohol) films as release agents, so it neither recommends nor tests them. An industrial release decision is made against a declared composition, a food-contact position and a cyclosiloxane declaration. A household product supplies none of the three, which is the reason this page says nothing further about them rather than a verdict on how they perform.

Is silicone mold release food safe?#

Not as a blanket statement: polydimethylsiloxane is authorised as a food-contact additive inside a plastic under FCM 575 of Regulation (EU) No 10/2011 and the grafted form is cleared as an extrusion aid under 21 CFR 177.1520, but neither is a clearance for a release agent sprayed on a tool. The FDA's release-agent section, 21 CFR 178.3860, lists fatty amides and waxes rather than silicones. Ask the supplier to name the instrument and the section it relies on, in writing, instead of accepting a food-grade label.

Does silicone mold release damage the mould?#

No tool-damage or corrosion data for silicone release agents is held in this reference; what is documented is accumulation, because a sacrificial film that is not carried away by the part builds up and a semi-permanent coating has to be stripped before the tool is recoated. Cleaning is therefore planned as part of the release system, and no cleaning chemistry or interval is published here.

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