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Comparing Single Component Liquid Silicone Rubber (RTV-1) and Two Component Liquid Silicone Rubber (RTV-2)

By 6.2 min readPublished On: May 22nd, 2023Last Updated: May 22nd, 2023Categories: Silicone industry knowledge

Liquid Silicone Rubber (LSR) is a versatile material widely used in various industries for its exceptional properties and applications. When it comes to LSR, it’s important to understand the distinction between two popular types: Single Component Liquid Silicone Rubber (RTV-1) and Two Component Liquid Silicone Rubber (RTV-2). In this article, we will explore the characteristics, advantages, and differences between RTV-1 and RTV-2, enabling you to make informed decisions based on your project requirements.


Section 1: Understanding RTV-1 Silicone Rubber

RTV-1 silicone rubber is a single component LSR that offers simplicity and convenience. It is pre-mixed and ready-to-use, requiring no additional components. RTV-1 exhibits faster curing through a condensation cure mechanism. This type of silicone rubber finds its advantages in applications that involve simpler molds and less complex designs. It offers ease of use, faster production cycles, and longer shelf life. However, it may have limitations in achieving higher ultimate properties and suitability for intricate parts.

Section 2: Exploring RTV-2 Silicone Rubber

RTV-2 silicone rubber is a two component LSR that provides greater versatility and customization options. It involves the mixing of a base and a curing agent, typically on-site. The addition cure mechanism of RTV-2 allows for controlled curing time, making it suitable for applications with complex molds and intricate parts. RTV-2 offers improved properties and can be further enhanced through post-curing. However, the mixing process is more involved, requiring careful measurement and blending. RTV-2 also has a shorter shelf life due to the reactive nature of its components, and it may involve higher costs due to the additional components.

Section 3: Key Differences between RTV-1 and RTV-2

To better understand the differences between RTV-1 and RTV-2, let’s compare them across various criteria:

Curing Mechanism:

RTV-1 utilizes condensation cure, while RTV-2 employs addition cure.


RTV-1 is a single component silicone rubber, whereas RTV-2 consists of two components: a base and a curing agent.

Mixing Process:

RTV-1 is pre-mixed and ready-to-use, while RTV-2 requires on-site mixing of the base and curing agent.

Curing Time:

RTV-1 generally has a shorter curing time, while RTV-2 offers variable and controllable curing time.

Application Suitability:

RTV-1 is suitable for simpler molds and applications, while RTV-2 is more versatile and can accommodate complex molds and intricate parts.

Post-Curing Required:

RTV-1 typically does not require post-curing, whereas RTV-2 may benefit from post-curing to enhance its properties.

Shelf Life:

RTV-1 has a longer shelf life compared to RTV-2, which has a limited shelf life due to its reactive components.

Section 4: Factors to Consider when Choosing RTV-1 or RTV-2

When selecting between RTV-1 and RTV-2, several factors should be considered:

Project Requirements and Specifications:

Consider the complexity of the mold or application, the desired physical properties, and the performance expectations.

Volume and Batch Size:

Evaluate the volume and batch size required for your project, as it can influence the choice between RTV-1 and RTV-2.

Time and Cost Considerations:

Assess the impact on production time, efficiency, and overall expenses associated with each type.

Post-Curing and Shelf Life:

Determine if post-curing is necessary for achieving specific properties and consider the shelf life limitations of RTV-2.


In summary, the choice between RTV-1 and RTV-2 liquid silicone rubbers depends on the specific requirements of your project. RTV-1 offers simplicity, faster curing, and longer shelf life, making it suitable for simpler molds and applications. On the other hand, RTV-2 provides versatility, enhanced properties, and customization options, making it ideal for complex molds and intricate parts. By considering factors such as project specifications, volume, time, cost, and desired properties, you can make an informed decision and harness the full potential of liquid silicone rubber for your application.


Comparison between RTV-1 and RTV-2 Liquid Silicone Rubbers:

CriteriaRTV-1 Silicone RubberRTV-2 Silicone Rubber
Curing MechanismCondensation cureAddition cure
CompositionSingle componentTwo components (base + curing agent)
Mixing ProcessPre-mixed and ready-to-useOn-site mixing of base and curing agent
Curing TimeRelatively shorterVariable and controllable
Application SuitabilitySuitable for simpler molds and applicationsSuitable for complex molds and intricate parts
Post-Curing RequiredGenerally not requiredMay require post-curing for enhanced properties
Shelf LifeLonger shelf lifeLimited shelf life due to reactive components
Advantages– Simple and convenient to useĀ  Faster curing process – Longer shelf life– Versatile and suitable for complex applications- Enhanced properties with post-curing- Customizable curing time
Disadvantages– Limited suitability for complex applications- Lower ultimate properties– More complex mixing process- Shorter shelf life- Higher cost due to multiple components


Frequently Asked Questions (FAQ) about RTV-1 and RTV-2 Liquid Silicone Rubbers

Q1: Can RTV-1 and RTV-2 be used interchangeably?

A: RTV-1 and RTV-2 have different characteristics and curing mechanisms. While they both belong to the liquid silicone rubber family, their suitability depends on the specific requirements of your project. It’s essential to understand the differences and choose the type that aligns with your application needs.

Q2: Do both RTV-1 and RTV-2 require a mold release agent?

A: RTV-1 and RTV-2 generally have good release properties, and a mold release agent may not always be necessary. However, it is recommended to evaluate the specific application and mold conditions to determine if a release agent is required for optimal demolding.

Q3: Can RTV-2 be used without post-curing?

A: RTV-2 can be used without post-curing, depending on the desired properties and application requirements. However, post-curing can enhance certain properties, such as heat resistance, tensile strength, and elongation. It is advisable to consult the manufacturer’s guidelines and conduct testing to determine the necessity of post-curing for your specific application.

Q4: Is RTV-1 or RTV-2 more cost-effective?

A: The cost-effectiveness of RTV-1 and RTV-2 depends on various factors, including project requirements, volume, and specific application needs. RTV-1 is generally simpler to use and has a longer shelf life, potentially reducing production time and material waste. RTV-2, while involving additional components and a more complex mixing process, offers versatility and enhanced properties. Consider the overall project scope and requirements to determine the cost-effectiveness of each type.

Q5: Can RTV-1 and RTV-2 be pigmented or colored?

A: Yes, both RTV-1 and RTV-2 can be pigmented or colored. Silicone pigments or colorants can be added during the mixing process to achieve the desired color or aesthetic requirements of the application. However, it’s important to ensure compatibility with the specific silicone rubber formulation and follow the recommended pigment dosage guidelines.

Q6: Can RTV-1 and RTV-2 be used for food-grade applications?

A: Yes, RTV-1 and RTV-2 liquid silicone rubbers can be formulated to meet food-grade standards. It is crucial to use silicone rubber materials that comply with relevant food-contact regulations and standards, such as FDA (Food and Drug Administration) or EU regulations, for applications involving direct or indirect contact with food.

Q7: Can RTV-1 and RTV-2 be used for medical or healthcare applications?

A: Yes, both RTV-1 and RTV-2 liquid silicone rubbers can be suitable for certain medical or healthcare applications. However, it is essential to ensure that the chosen silicone rubber formulation complies with the necessary medical-grade standards and regulations, such as USP Class VI or ISO 10993, depending on the intended use.

Q8: Are RTV-1 and RTV-2 suitable for high-temperature applications?

A: RTV-1 and RTV-2 silicone rubbers exhibit varying levels of heat resistance. RTV-2, especially with post-curing, can achieve higher temperature resistance compared to RTV-1. It is advisable to consult the manufacturer’s technical datasheets and guidelines to determine the recommended maximum continuous operating temperature for each specific formulation.