Rubber Mold Release

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Release Agents for the Rubber Industry

McLube® has manufactured rubber mold release agents and anti-tack coatings for over fifty years. Our consummate line of mold release agents for natural and synthetic rubbers will protect mold surfaces from harmful compounds, dramatically reduce substrate microporosity, and stand up to the most abrasive rubbers for long-lasting release. We offer cost-effective, water and solvent-based release agents to include semi-permanent and sacrificial coatings. McLube® also offers mold release sprays for rubber molding applications. Explore below for more information or contact us today for process assistance and samples.

Supported Rubber Materials

Ethylene Propylene Diene monomer ( EPDM )
FKM and other fluoroelastomers (Viton ®, Aflas ®)
Silicone rubber, nitrile, BUNA, and natural rubbers, Isoprene
HNBR, Butyl, polychloroprene, SBR, Neoprene
Peroxide- and sulfur-cured rubbers
EVA / PEVA
Styrene butadiene rubber (SBR)
ECO, CPE, re-vulcanized crumb rubber, and more

Supported Processes

Compression molding
Rubber to metal bonding
Injection molding
Extrusion
Transfer molding
Tire manufacturing
Hose manufacturing (mandrel-built rubber parts)
Re-bonded crumb rubber
Rubber shoe outsoles

Featured Rubber Mold Release Agents

Product	Base	Type	Description	Recommended for
McLube® 860	Water	Heat-cured	Semi-permanent, durable, non-transferring, PFAS-free	FKM, EPDM, HNBR, nitrile, neoprene, and peroxide-cured
McLube® 1711L	Solvent	Instant Cure	Semi-permanent, non-transferring, silicone-free.	General molding and silicone rubbers
McLube® 1725L	Solvent	Instant Cure	Semi-permanent, non-transferring	EPDM, SBR, nitrile, natural; injection molding, composite applications
McLube® 1805	Solvent	Heat-cured	Multiple releases per application, PFAS-free	General rubber molding, peroxide-cured compounds
McLube® 1901	Water	Conventional	PFAS-free, silicone-free, multiple releases	General rubber molding, silicone rubber
McLube® 3030	Water	Heat-cured	Semi-permanent, PFAS-free, extended shelf-life	FKM, EPDM, HNBR, nitrile, neoprene, and peroxide-cured

* This is a list of featured products only. All McLube® products for rubber molding applications are not listed on this page. If you do not see the McLube® product you currently use listed above, this does not mean it has been discontinued. Contact Us to inquire about a product that is not listed above.

Specialty Rubber Applications

Tire Manufacturing

Hose Manufacturing

Crumb Rubber

Optimizing the release agent for your rubber molding process?

We are here to help from product selection to testing and ongoing support.

Rubber Mold Release FAQs

How do I prevent knit lines?

Knit lines occur when the rubber flow front pushes excess or uncured release agent through the cavity, preventing the material from “fusing.” Steps rubber molders can take include avoiding overapplication, switching to a semi-permanent coating, or ensuring that the semi-permanent release is properly cured.

Reduce Application: Overapplication of release agent is a common cause of knit lines. This is especially common when using “sacrificial” release agents. To avoid knit lines and “puddling” in the mold cavity, reduce application volume or frequency of reapplication. Apply thin, even coatings. If diluting, rubber molders may also consider increasing the dilution ratio as well.

Upgrade to Semi-Permanent Release Agent: If you are unable to prevent knit lines by reducing application of your sacrificial release agent, or parts are too difficult to release at lower application rates, then consider switching to a semi-permanent release agent.

Ensure Proper Cure: follow instructions found in the product’s technical documentation (TDS). Knit lines may occur if a semi-permanent release is not given sufficient time to cure and bond to the mold surface.

How do I prevent in-mold buildup?

The most common causes of in-mold buildup are excess release coating in the mold cavity or coating degradation over time. These issues are commonly solved by optimizing application methods, namely ensuring proper mold prep and consistent application procedures while avoiding overapplication.

Consistency: ensure all shifts follow application procedures, including cleaning procedures.
Proper mold prep: Was the mold properly cleaned before the release agent was applied? Residual fouling in the mold will promote buildup and may prevent release agents from performing properly. Use a cleaning solvent or other methods such as bead blasting to remove all mold buildup and then reapply your release agent according to technical instructions.
Dilution ratio (if applicable): consider diluting water-based release agents 1:1 or increasing current dilution ratio. Systematically test dilution ratios to find the ideal balance between reduced fouling, part appearance, and release performance.
Choice of release agent: If buildup cannot be resolved, rubber molders may consider switching to a release agent that is more suited to their process conditions and material.