Tin-cured silicone rubber, also known as condensation-cure silicone rubber, comprises two sections: part A, usually a white or translucent viscous base, and part B, a clear to slightly yellowish curing agent. When these two components are mixed in a weight ratio of 100A:3B, they cure to form elastic silicone rubber when exposed to ambient moisture in the environment at room temperatures (20-30°C/68-86℉). After curing, silicone displays relatively good tear resistance, and its brittleness depends on the chosen hardness level. They can be poured onto models or made brushable by adding a thixotropic additive.

tin cured liquid silicone

Composition: Part A is a mixture of polyorganosiloxanes, fillers, and additives. Part B mainly contains 70% dibutyltin dilaurate and 30% dibutyltin dioctoate.

Curing Principle: Condensation-cure silicone employs tin salts as catalysts to initiate the transition from liquid to solid state. Two conditions must be met for curing to occur, namely moisture in the air and the presence of a catalyst. The vulcanization time is primarily determined by the catalyst ratio and temperature. A higher quantity of catalyst results in faster vulcanization and shorter operating times. Generally speaking, higher temperatures and humidity lead to faster curing times. To extend the working time of the material, temperature can be lowered or the amount of curing agent reduced. During curing, by-products such as acetic acid, amines, or alcohol are produced, leading to slight shrinkage in the cured silicone.

Features

Technical Parameter

Product NameHardnessMixing RatioViscosity (A)Pot LifeCure TimeTear Strength
RTV-31055 A100A:3B13,000 cps35 mins10 hrs≥8.0 N/mm
RTV-311010 A100A:3B15,000 cps35 mins10 hrs≥12.0 N/mm
RTV-311515 A100A:3B18,000 cps35 mins10 hrs≥15.0 N/mm
RTV-3120 hot20 A100A:3B21,000 cps35 mins12 hrs≥23.0 N/mm
RTV-3125 hot25 A100A:3B23,000 cps35 mins12 hrs≥24.0 N/mm
RTV-3130 hot30 A100A:3B24,000 cps35 mins12 hrs≥23.0 N/mm
RTV-314038 A100A:3B25,000 cps35 mins12 hrs≥19.0 N/mm
Product NameHardnessMixing RatioViscosity (A)Pot lifeCure TimeTear Strength
RTV-32055 A100A:3B13,000 cps35 mins10 hrs≥9.0 N/mm
RTV-321010 A100A:3B15,000 cps35 mins10 hrs≥13.0 N/mm
RTV-321515 A100A:3B18,000 cps35 mins10 hrs≥16.0 N/mm
RTV-322020 A100A:3B21,000 cps35 mins12 hrs≥24.0 N/mm
RTV-322525 A100A:3B23,000 cps35 mins12 hrs≥25.0 N/mm
RTV-323030 A100A:3B24,000 cps35 mins12 hrs≥24.0 N/mm
RTV-324037 A100A:3B25,000 cps35 mins12 hrs≥20.0 N/mm
tin cure silicone material

Application Examples

The condensation-cure (tin-catalyst) silicone material is a high-strength rubber specifically developed for the creation of prototype designs and production tools, particularly in the realm of rapid prototyping. It is the preferred material for many mold makers and casting artists due to its excellent flexibility, superior strength, enhanced resistance, and long lifespan.

Tin-cure silicones are capable of casting a variety of materials, including wax, gypsum, low-melt alloys/metals, and urethane, epoxy or polyester resins. They are also used to make molds for tire production and development of new tires.

Tin silicone molds are highly versatile and can be utilized for creating a wide range of decorative items. They are particularly well-suited for producing architectural elements, block-outs and hole formers, concrete countertops, flexible form liners, GFRC (Glass Fiber Reinforced Concrete), manufactured stone veneer, cornices, statuary, stamped and textured concrete, among other applications.

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Attention

To ensure proper curing, it is important to use the base and catalyst that are provided together in the same kit. Mixing one brand's hardener with another brand's silicone may result in the mixture failing to properly cure.

As no two applications are exactly the same, it is recommended to conduct a small test application when determining the suitability of this material for your project, especially if there are concerns about its performance.

It is recommended to employ a vacuum chamber for vacuum degassing the mixed material, effectively eliminating any trapped air.

tin cure silicone rubber

Tin-cured silicone requires air and moisture to cure properly, which makes it unsuitable for use in confined spaces.

Curing tin-cured silicone at temperatures below 10°C (50°F) is not recommended, as it may be difficult to cure properly. Curing at room temperature (20-30°C/68-86℉) helps to minimize shrinkage rate. It should be noted that heat curing is only effective up to 45°C (113°F); heating the material above this temperature will not accelerate the curing process.

After use, it is important to tightly close the catalyst containers. If left exposed to air for extended periods of time, tin-catalyst may hydrolyze. An indication of hydrolysis is the formation of a film or crust on the surface of the catalyst. The use of hydrolyzed catalyst is not recommended and may result in incomplete curing.

condensation cure silicone rubber

Safety

It is not recommended for children under the age of 16 to use tin-cured liquid silicone. Even though many of our liquid silicone rubber products are considered "non-toxic", they are still liquid chemicals and can cause irritation.

Tin-cured silicone does have a certain odor, and therefore it is recommended to work in a well-ventilated environment. If ventilation is not adequate, respiratory protection should be worn. If you experience any unpleasant symptoms, please move to an area with fresh air. Avoid splashing the material into your eyes, but if it does occur, rinse immediately with plenty of water and seek medical attention. Wearing rubber gloves can help minimize skin contact.

Tin-cured silicone is an industrial silicone rubber and should not be used for food molding, dental, or human skin molding applications.

tin cure mold making silicone

Storage

Tin-cured silicone raw material can be stored at temperatures between 15°C (60°F) and 25°C (77°F) for up to 12 months from its date of manufacturing. Storing the material at warmer temperatures will reduce the usable shelf life of unused material. Exceeding the storage time beyond the date specified on the certificate of analysis does not necessarily mean that the product is no longer usable. However, the properties required for the intended use must be checked for quality assurance reasons in this case.

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