Platinum-cured and peroxide-cured silicone can look almost identical after molding, but the chemistry used to crosslink the rubber is very different. That difference can affect odor, volatile residues, post-curing, transparency, process control, material cost and suitability for sensitive applications.
For many buyers, the question is simply: “Is platinum-cured silicone better?”
The more useful engineering question is: “Which curing system is appropriate for the product, manufacturing process and compliance requirements?”
This guide compares platinum-cured and peroxide-cured silicone and explains when each system makes sense.
Quick Answer: Platinum Cure vs Peroxide Cure
| Factor | Platinum-Cured Silicone | Peroxide-Cured Silicone |
|---|---|---|
| Cure chemistry | Addition cure / hydrosilylation | Free-radical curing using organic peroxide |
| Reaction byproducts | No curing-reaction byproducts | Peroxide decomposition byproducts are formed |
| Post-curing | Application dependent; may still be required | Often important for removing curing residues and odor |
| Odor after cure | Typically low | Can have characteristic odor before adequate post-cure |
| Transparency | Often well suited to clear applications | Depends strongly on formulation |
| Cure inhibition | Sensitive to sulfur, amines, tin and certain contaminants | Generally less sensitive to platinum catalyst poisons |
| Material cost | Often higher | Often more economical for general HCR applications |
| Typical applications | LSR, food-contact, baby, medical and precision applications where an approved grade is selected | General industrial HCR, molded parts, profiles, seals and other suitable applications |
Neither curing system should be selected by name alone. The specific silicone grade, mechanical properties, applicable regulations and manufacturing conditions still need to be reviewed.
What Does “Curing” Mean in Silicone Rubber?
Before curing, silicone polymer does not yet have the stable three-dimensional network required for a finished elastomeric component.
During curing, chemical crosslinks form between polymer chains. The material changes into a flexible solid that can maintain its shape while still stretching and recovering.
Two common systems used for heat-cured silicone rubber are:
- platinum-catalyzed addition curing
- peroxide curing
The choice of cure system affects much more than how quickly the silicone becomes solid.
What Is Platinum-Cured Silicone?
Platinum-cured silicone is also called addition-cure silicone.
The system commonly uses:
- vinyl-functional silicone polymers
- silicone hydride crosslinkers
- a platinum catalyst
The platinum catalyst enables a hydrosilylation reaction between the vinyl and Si-H functional groups. This builds the crosslinked elastomer network.
This is one reason platinum-cured systems are widely used in liquid silicone rubber and in applications where low odor and controlled extractables or volatiles are important.
Modern liquid silicone rubber (LSR) is generally a two-component platinum-cured system designed for automated injection molding.
What Is Peroxide-Cured Silicone?
Peroxide-cured silicone uses an organic peroxide curing agent.
When heated, the peroxide decomposes and produces reactive free radicals. These initiate crosslinking between silicone polymer chains.
Unlike platinum addition cure, peroxide chemistry can create decomposition products during the curing reaction.
Depending on the peroxide system, these residual compounds may contribute to:
- odor
- surface deposits or blooming
- volatile residues
- additional post-curing requirements
For this reason, peroxide-cured silicone components are often post-cured when residual volatile content or odor is important.
Peroxide curing remains widely used in HCR / HTV silicone and can be an economical and effective option for many industrial components.
Platinum Cure Produces No Reaction Byproducts — But That Does Not Mean “No Post-Cure”
This distinction is important.
Platinum-catalyzed addition cure does not create the decomposition products associated with peroxide curing.
However, a platinum-cured silicone article may still contain:
- low-molecular-weight silicone components
- volatile constituents from the material formulation
- residual processing-related volatiles
Post-curing may therefore still be used to:
- reduce volatile content
- improve certain mechanical properties
- improve compression-set performance
- meet application-specific food-contact requirements
- meet selected medical or sensitive-use specifications
Why Is Post-Curing More Important for Peroxide-Cured Silicone?
With peroxide curing, the curing agent decomposes during vulcanization. The resulting compounds may remain temporarily in the silicone.
Post-curing typically involves heating finished parts in a ventilated oven for a defined period.
Its purpose may include:
- removing peroxide decomposition products
- reducing odor
- reducing volatile extractables
- stabilizing material properties
The required time and temperature depend on the silicone compound and intended application.
A generic post-cure schedule should therefore not be copied from another product without checking the material supplier's processing guidance.
Platinum-Cured Silicone Is Sensitive to Cure Inhibition
One disadvantage of platinum-catalyzed systems is their sensitivity to certain contaminants.
Some substances can interfere with the platinum catalyst and prevent proper crosslinking.
Known inhibitor families include:
- sulfur-containing compounds
- amines and amides
- organotin compounds
- some phosphorus compounds
- certain plasticizers
- some pigments, primers and surface treatments
A contaminated area may remain:
- sticky
- soft
- partially cured
- completely uncured
This is particularly important for:
- overmolding onto plastics
- silicone-to-metal bonding
- colored silicone
- adhesive interfaces
- multi-material assemblies
Dow specifically identifies sulfur compounds, amines and organotin compounds among common platinum-cure inhibitors.
Why Pigments Matter in Platinum-Cured Silicone
Pigment selection is not purely a color-matching decision.
A pigment system that contains incompatible additives can interfere with platinum curing.
For this reason, production pigments should be formulated specifically for compatibility with the selected silicone cure system.
We recommend approving:
- the silicone grade
- the cure system
- the pigment formulation
- the final Pantone target
before locking final production samples.
For more information, see: How to Choose Safe Pigments for Colored Baby Silicone Products and our Silicone Pantone Color Matching Guide.
Platinum-Cured vs Peroxide-Cured Silicone for Food Contact
Platinum-cured silicone is commonly selected for food-contact products because addition cure produces no peroxide decomposition byproducts and can offer low odor and clean processing.
However:
Food-contact suitability depends on the specific silicone formulation and the applicable regulatory requirements.
A buyer may need documentation or testing related to requirements such as:
- FDA food-contact requirements
- German BfR recommendations
- LFGB-related migration testing
- EU food-contact requirements
- application-specific extraction or migration limits
A suitable peroxide-cured formulation can also be used for food-contact applications when the compound and final production process meet the applicable requirements.
Therefore, cure chemistry alone should never replace documentation for the actual material or finished product.
For a broader explanation, see our What Is Food-Grade Silicone? guide.
Platinum-Cured vs Peroxide-Cured Silicone for Medical Applications
Medical silicone projects often favor platinum-cured materials because of their clean addition-cure chemistry and availability in medical-grade LSR and HCR families.
But the term “medical-grade silicone” cannot be defined by cure chemistry alone.
A medical component may require consideration of:
- specific raw-material grade
- ISO 10993 testing where applicable
- USP requirements where applicable
- manufacturing environment
- traceability
- bioburden control
- cleanroom production
- sterilization compatibility
- device classification
- finished-part validation
Therefore:
For medical silicone manufacturing information, see our Medical Silicone Products Manufacturing page.
Does Platinum-Cured Silicone Have Less Odor?
Generally, platinum-cured addition systems can achieve lower curing-related odor because the addition reaction does not generate peroxide decomposition products.
Peroxide-cured silicone may have a characteristic odor after molding if decomposition products remain.
Correct post-curing can significantly reduce these residues and odors.
However, odor can also be influenced by:
- raw material grade
- pigments
- additives
- processing contamination
- packaging
Cure system is therefore important, but it is not the only factor.
Which Cure System Gives Better Transparency?
Platinum-cured silicone is commonly used where high clarity or translucency is required.
This is particularly relevant for:
- medical components
- optical silicone
- transparent tubing
- consumer products
- inspection windows
However, final clarity still depends on:
- silicone grade
- filler system
- pigment
- surface finish
- part thickness
- processing conditions
“Platinum-cured” should therefore not be interpreted as a guarantee that every material will be optically clear.
Does Cure System Affect Mechanical Properties?
Yes, but cure chemistry alone does not determine whether a silicone is stronger.
Two silicone materials with the same Shore A hardness can have different:
- tensile strength
- tear strength
- elongation
- compression set
- rebound
- fatigue performance
These properties depend on the complete formulation, not just whether platinum or peroxide was used.
For this reason, do not specify:
“Platinum silicone, 50 Shore A”
and assume that all 50A platinum grades will perform identically.
See our Silicone Rubber Hardness Guide for a more detailed explanation.
Platinum Cure vs Peroxide Cure in LSR and HCR
Another common misunderstanding is assuming:
- LSR = platinum
- HCR = peroxide
The first statement is generally true for modern commercial LSR: it is typically supplied as a two-component platinum-cured system.
HCR, however, can use either:
- peroxide curing
- platinum addition curing
| Material System | Common Cure Options |
|---|---|
| LSR | Primarily platinum addition cure |
| HCR / HTV | Peroxide cure or platinum addition cure |
This is why material form and cure chemistry should be listed as separate specifications.
How Cure System Affects Production Process
Platinum-Cured LSR
LSR is commonly supplied as two components that are accurately metered and mixed before injection.
The system supports:
- closed material handling
- automated injection molding
- rapid cure cycles
- multi-cavity production
- high repeatability
This makes LSR attractive for precision and higher-volume manufacturing.
Peroxide-Cured HCR
Peroxide-curing agents are typically incorporated into high-consistency silicone compounds before molding or extrusion.
These materials can be processed by:
- compression molding
- transfer molding
- injection molding
- extrusion
- calendering
For molded HCR components, silicone compression molding can provide an economical solution for many part sizes and production quantities.
Which One Costs More?
Platinum-cured silicone materials are often more expensive than comparable general-purpose peroxide-cured HCR compounds.
However, raw-material price is only one part of total manufacturing cost.
The actual project cost also depends on:
- tooling
- molding cycle time
- automation
- post-curing
- labor
- deflashing
- scrap rate
- quality requirements
- production volume
For example, a higher-cost platinum LSR material used in an automated multi-cavity mold can still achieve competitive unit economics at high production volume.
Likewise, peroxide-cured HCR can remain highly economical for many compression-molded industrial components.
For the complete cost structure, see our Custom Silicone Molding Cost Guide.
When Should You Choose Platinum-Cured Silicone?
Platinum-cured silicone should be strongly considered when the project requires:
- LSR injection molding
- very low curing-related byproducts
- low odor
- high transparency
- precision automated production
- selected food-contact applications
- baby-care products
- selected medical applications
- clean processing requirements
However, the actual production material still needs to meet the project's regulatory and mechanical requirements.
When Does Peroxide-Cured Silicone Make Sense?
Peroxide-cured silicone can be a practical choice for:
- general industrial seals
- gaskets
- extruded profiles
- pads
- large compression-molded components
- applications where the selected peroxide HCR already meets the required specifications
- cost-sensitive applications where platinum cure provides no functional advantage
It should not automatically be considered “low quality.”
A correctly selected, processed and post-cured peroxide silicone can provide excellent mechanical and thermal performance.
Is Platinum-Cured Silicone Always Better?
No.
It is cleaner from the standpoint of curing reaction byproducts and is particularly useful for sensitive applications, but it also introduces:
- higher raw-material cost in many cases
- greater sensitivity to cure inhibitors
- stricter requirements for compatible pigments and substrates
- more controlled material handling
If a simple industrial gasket performs perfectly using a qualified peroxide-cured HCR, changing it to platinum-cured silicone may add cost without adding functional value.
Material selection should therefore start from application requirements rather than marketing terminology.
How Cure System Can Affect Mold Design
The curing method can influence manufacturing conditions, but mold design also depends heavily on whether the material is LSR or HCR.
Engineers need to consider:
- material viscosity
- flow behavior
- gate design
- venting
- parting-line precision
- cure temperature
- shrinkage
- demolding
LSR's very low uncured viscosity, for example, means mold shut-offs must be designed carefully to control flash.
For design guidance, see our Silicone Injection Molding Design Guide.
Does Cure System Affect Silicone Shrinkage?
The cure system is one variable that can influence material behavior, but shrinkage should never be estimated from “platinum” or “peroxide” alone.
Shrinkage also depends on:
- specific silicone grade
- hardness
- filler loading
- mold temperature
- post-cure
- part geometry
Always use the actual supplier data for the selected material.
Read our Silicone Rubber Shrinkage Guide for mold-compensation guidance.
Buyer Checklist: What to Ask Your Silicone Manufacturer
Instead of simply asking:
“Do you use platinum silicone?”
ask the following:
- What exact silicone material grade will be used?
- Is it LSR or HCR?
- Is the compound platinum-cured or peroxide-cured?
- Is post-curing required for this grade and application?
- What Shore A hardness will be used?
- Can you provide the relevant material technical data?
- What food-contact or medical documentation is available if required?
- Are the pigments compatible with the cure system?
- Are any plastic or metal substrates compatible with platinum curing?
- Will final inspection occur before or after post-curing?
Platinum vs Peroxide Selection Guide
| Project Requirement | Likely Starting Direction |
|---|---|
| Automated LSR injection molding | Platinum-cured LSR |
| Transparent precision component | Evaluate platinum-cured grades |
| Baby feeding product | Often platinum-cured, with required food-contact documentation |
| Medical device component | Evaluate appropriate medical-grade platinum-cured LSR/HCR and validation requirements |
| General industrial compression-molded gasket | Compare peroxide and platinum HCR based on performance and cost |
| Industrial extrusion | Either system may be appropriate depending on material requirements |
| Application highly sensitive to odor or curing residues | Platinum cure generally has an advantage |
| Cost-sensitive non-regulated industrial part | Peroxide HCR may be economical if performance is suitable |
Common Mistakes When Choosing a Silicone Cure System
Mistake 1: Assuming Platinum Means Food Grade
Platinum describes the curing chemistry. Food-contact compliance must be verified separately.
Mistake 2: Assuming Peroxide Silicone Is Unsafe
The suitability of a peroxide-cured product depends on the specific material, processing, post-cure and intended application.
Mistake 3: Assuming Platinum Silicone Never Needs Post-Curing
Post-curing may still be recommended or required to reduce volatiles or meet selected performance and regulatory requirements.
Mistake 4: Ignoring Cure Inhibition
A substrate, pigment, adhesive or contaminant can prevent platinum silicone from curing correctly. Compatibility testing should be performed when there is uncertainty.
Mistake 5: Choosing the Cure System Before Defining the Application
Start with temperature, mechanical, regulatory, dimensional and production requirements. Then select the silicone material and curing method.
Frequently Asked Questions
What is platinum-cured silicone?
Platinum-cured silicone is an addition-cure silicone system that uses a platinum catalyst to promote crosslinking between vinyl-functional silicone and hydride-containing crosslinkers. The curing reaction does not produce decomposition byproducts.
What is peroxide-cured silicone?
Peroxide-cured silicone uses an organic peroxide that decomposes under heat to create reactive free radicals that crosslink the silicone polymer. The reaction creates decomposition products that may require post-curing to remove.
Is platinum-cured silicone food grade?
Not automatically. A platinum-cured material must still meet the applicable food-contact requirements for the intended market and application. Always verify the specific compound and supporting documentation.
Is peroxide-cured silicone food safe?
Some peroxide-cured silicone formulations may be suitable for food-contact applications when correctly manufactured and post-cured and when they meet the applicable regulatory requirements. The cure method alone does not determine compliance.
Does platinum-cured silicone need post-curing?
Sometimes. Addition cure does not generate peroxide decomposition byproducts, but post-curing may still be used to reduce volatiles, improve certain properties or meet specific food-contact or medical requirements.
Why does peroxide silicone need post-curing?
Post-curing is commonly used to remove residual peroxide decomposition products, reduce odor and stabilize the material after molding.
Which silicone cure system is more expensive?
Platinum-cured materials are often more expensive than general-purpose peroxide-cured HCR, but total component cost depends on tooling, cycle time, automation, post-curing, labor and production volume.
Can HCR silicone be platinum cured?
Yes. High-consistency silicone rubber can be formulated using either peroxide curing or platinum addition curing.
Is LSR always platinum cured?
Commercial liquid silicone rubber used for injection molding is generally supplied as a two-component platinum-catalyzed addition-cure system. Always verify the specific material data sheet for the selected grade.
What can inhibit platinum silicone curing?
Known inhibitors include sulfur-containing compounds, amines, organotin compounds and certain other contaminants, additives, pigments or surface treatments. Compatibility testing is recommended when the contacting material is uncertain.
Final Takeaway
Platinum-cured and peroxide-cured silicone are both established manufacturing technologies. The correct choice depends on the finished product rather than on which curing system sounds more premium.
Peroxide cure generates decomposition products and commonly requires post-curing.
Platinum cure can still require post-curing for sensitive applications.
Platinum-cured does not automatically mean food grade or medical grade.
Peroxide-cured does not automatically mean low quality.
Select the actual silicone grade according to application, processing and compliance requirements.
Not Sure Which Silicone Cure System to Use?
SILICONE SOLUTION can review your product application, material requirements, Shore hardness, production volume and compliance requirements before tooling.
We support custom silicone projects from material selection and DFM through mold manufacturing, sampling and mass production.
Discuss Your Silicone Material RequirementsTechnical References
WACKER — Solid and Liquid Silicone Rubber: Material and Processing Guidelines
Momentive — Liquid Silicone Rubber Material and Cure Technology
Momentive — Heat Cured Rubber: Platinum and Peroxide Cure Systems
Dow — Platinum-Catalyzed Silicone Cure Inhibitors
Material and regulatory requirements vary by formulation and end use. Always verify the specific production material, processing instructions and applicable compliance requirements before final material approval.
Enrique
Hi, I am the author of this article. For the past 10 years or so, we have been dedicated to meeting the custom silicone product needs of our customers from over 50 countries and regions around the world. If you have any questions, please contact us for a free, no-obligation quote.
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