Tin-cured silicone rubber, also known as condensation-cured silicone rubber, is an RTV-2 silicone rubber composed of two parts: Part A, a white or translucent viscous material, and Part B, a clear to yellowish tin-based catalyst.

When mixed in a ratio of 100:2 to 100:4 by weight, the silicone reacts with atmospheric moisture to form a flexible, durable elastomer. Offering excellent tear strength and release properties, it can be poured for block molds or made brushable for blanket molds by adding a thixotropic agent.

tin cured silicone rubber

Curing Principle

Condensation curing is a process initiated by a tin-based catalyst that promotes a reaction between hydroxyl-terminated polymers, requiring atmospheric moisture to proceed. The cure rate is influenced by the catalyst ratio, ambient temperature, and humidity; increasing any of these factors will shorten both the working and curing times. A key feature of this reaction is the release of small by-products (e.g., acetic acid, amines, or alcohol), which causes slight, gradual shrinkage as the elastomer solidifies.

FEATURES

  • Wide Hardness

    5-40 Shore A.

  • Detail Reproduction

    Captures finest textures.

  • High Tear Strength

    Durable for mold making.

  • Low Shrinkage

    ≤0.3% linear shrinkage.

  • Processing

    Pourable or Brushable.

  • Easy Demolding

    Excellent release properties.

  • Heat Resistance

    Up to 200°C (392°F).

  • RTV-2

    Room temperature cure.

APPLICATIONS

Tin-cured silicone rubber is a cost-effective and durable mold-making material, valued for its high tear strength and excellent demolding properties. It is the preferred choice for a wide range of industrial, artistic, and architectural applications where durability and reliability are essential. Its ability to capture fine detail makes it ideal for creating production tools, prototype designs, and decorative items using materials such as resins (urethane, epoxy, polyester), wax, gypsum, concrete, and low-melt metals.

View More

TECHNICAL DATA

Product NameHardnessMixing RatioViscosity (A)Pot LifeCure TimeTear Strength
RTV-31055 A100A:3±1B15,000 cps40 mins8 hrs8.0 N/mm
RTV-311010 A100A:3±1B15,000 cps40 mins8 hrs12.0 N/mm
RTV-311515 A100A:3±1B16,000 cps40 mins9 hrs16.0 N/mm
RTV-312020 A100A:3±1B21,000 cps40 mins9 hrs25.0 N/mm
RTV-312525 A100A:3±1B20,000 cps40 mins10 hrs25.0 N/mm
RTV-313030 A100A:3±1B19,000 cps40 mins10 hrs25.0 N/mm
RTV-313535 A100A:3±1B18,000 cps40 mins11 hrs23.0 N/mm
RTV-314038 A100A:3±1B18,000 cps40 mins12 hrs21.0 N/mm
white tin cured silicone rubber
Product NameHardnessMixing RatioViscosity (A)Pot LifeCure TimeTear Strength
RTV-32055 A100A:3±1B15,000 cps40 mins8 hrs9.0 N/mm
RTV-321010 A100A:3±1B15,000 cps40 mins8 hrs13.0 N/mm
RTV-321515 A100A:3±1B16,000 cps40 mins9 hrs17.0 N/mm
RTV-322020 A100A:3±1B21,000 cps40 mins9 hrs26.0 N/mm
RTV-322525 A100A:3±1B20,000 cps40 mins10 hrs26.0 N/mm
RTV-323030 A100A:3±1B19,000 cps40 mins10 hrs26.0 N/mm
RTV-323535 A100A:3±1B18,000 cps40 mins11 hrs24.0 N/mm
RTV-324037 A100A:3±1B18,000 cps40 mins12 hrs22.0 N/mm
translucent tin cured silicone rubber

Catalyst Handling & Mixing Ratio

Warning: The Part B catalyst is sensitive to moisture. Prolonged exposure to air can cause hydrolysis (formation of a surface film or crust). Immediately reseal the container tightly after every use.
  • Matching Kit: Always use components from the same kit. Test compatibility if mixing different batches.
  • Adjustable Range: 100:2 to 100:4. Higher catalyst ratio accelerates curing; lower ratio extends working time.
  • Mix by Weight: Use an electronic scale for precise weighing. Do not estimate by volume.

Processing Conditions

  1. Compatibility: Always conduct a small-scale test before applying to the full model to ensure no reaction with the substrate.
  2. Temperature: Best results at 20–30°C (68–86°F). Curing may fail below 10°C (50°F).
  3. Moisture Requirement: Tin-cured silicone requires atmospheric moisture to cure. Do not use in completely confined/airtight spaces.
  4. Heat Acceleration: Limited effectiveness. Only effective up to 45°C (113°F). Temperatures above this will not significantly speed up cure.

Safety Precautions

INDUSTRIAL USE ONLY: Not suitable for food molding, dental applications, or direct skin contact.
  • Ventilation: Use in a well-ventilated area to disperse by-products (alcohols/amines). Wear respiratory protection if ventilation is inadequate.
  • Protection: Always wear safety glasses and liquid-tight gloves (nitrile or butyl). Avoid splashing into eyes or skin.
  • First Aid: In case of eye contact, rinse immediately with plenty of water and seek medical attention.
  • Children: Keep out of reach of children.

Storage & Shelf Life

Storage Conditions
Store in a cool, dry place at room temperature (15–25°C / 60–77°F). Keep away from direct sunlight.
Shelf Life
12 months from the date of manufacture when stored properly. High temperatures will shorten shelf life.
Opened Containers
Reseal immediately to prevent leakage and catalyst hydrolysis.
Beyond Shelf Life: If stored beyond its shelf life, the product may still be usable. However, the user is responsible for testing and confirming its performance and suitability for the intended application before use.
condensation silicone rubber
Community Q&A