What Grades of Silicone Rubber are Available?

There are a huge variety of silicone rubber grades available. Silicone or polysiloxane is a polymer that is made

There are a huge variety of silicone rubber grades available. Silicone or polysiloxane is a polymer that is made up of the functional group siloxane. Siloxane is a chain of silicon and oxygen atoms that are frequently combined with carbon and hydrogen.

 Silicone rubber is an elastomer that is non-reactive, highly stable and resistant to all manners of chemicals and temperatures. Due to these physical properties, silicone is frequently used in industries from pharmaceuticals to automotive. 

General Purpose Silicone Rubber


General-purpose grades of silicone are used across a vast range of industries and applications due to their incredibly versatile properties. They can operate in low temperatures and also, thanks to their heat resistance, in very high temperatures. They are also naturally translucent and can be easily pigmented to match any required colour.

The general-purpose silicone rubbers are perfect for extrusion profiles and silicone moulds for mould making. They are also commonly used in both tubing and sealants for the food and pharmaceutical industries as well as silicone parts in the automotive industry and electrical insulation as they are non-stick, with incredible tensile strength and chemical resistance.

Weather Resistant Silicone Rubber 


Silicone is undoubtedly one of the most impressive weatherproof polymers. This makes it a brilliant choice if your application will see tough environmental conditions where weathering can typically occur.

Silicone offers phenomenal technical properties when met with harsh conditions. Where other rubbers would crack and harden over time, silicones‘ resistance to UV light, ozone, oxygen salt and more helps them to stay intact through tough conditions.

Heat Stabilised Silicone Rubber


Heat Stabilised grades of silicone contain an additive enabling them to operate at temperatures up to 260°C. These are available from 30° Shore A to 80° Shore A.

This grade‘s ability to withstand such extreme temperatures makes it useful for soo many applications. Because of its impressive elasticity as a polymer, the rubber can actually stretch with the impact of the heat and subsequently go back to its original form once cooled down to around room temperature.

High-Temperature Silicone Rubber


This grade of silicone rubber is brilliant for a vast range of applications, this is because it has limited pigment due to cream coloured based material and has a maximum operating temperature of up to 300°c. It is available in a range of hardness from 40 Shore A to 80 shores A.

High Tear Strength Silicones 


High tear strength grades of silicone are FDA approved and are available from 50° Shore A to 70° Shore A. Naturally, these polymers are translucent, however, they can be pigmented to any colour you may require.

The particular grade is specifically designed to have higher elongation and tear strength than general-purpose silicone. It is commonly used for mouldings and gaskets as it is more resistant to abrasion.

Inflatable Grade Silicones


VINF60 is a specialised grade of silicone developed by Viking Extrusions specifically for the manufacture of inflatable seals. It has a high tear strength, is FDA approved and can be pigmented into any colour.

Inflatable silicone seals also commonly known as pneumatic seals are made from a hollow extruded profile which is joined into an air-tight seal.

Steam Resistant Silicone Rubber


Silicone rubber is often required in applications where steam is typically present. This is because there are often extremely high temperatures and pressure. Unlike most other polymers, silicone performs very well when met with steam.

Platinum Cured Silicone


Silicone rubber may be cured by either a platinum-catalyzed cure system, a condensation cure system, a peroxide cure system, or even an oxime cure system. Platinum cured silicone is a silicone rubber that has been through a curing process where the elastomer’s two parts become crosslinkers. Also known as addition cure silicone rubber, it exhibits the lowest long-term shrinkage and has longer shelf lives than other mould rubbers.

During the curing time, the rubber is crosslinked using a platinum catalyst rather than a peroxide catalyst used for other silicone grades. This material does not require post-curing, is more optically translucent and has a high tear strength.

Find out the differences between platinum-cured silicone and peroxide-cured cured silicone.

Liquid Silicone Rubber


Liquid silicone rubber is a grade that is very versatile and can be used in a variety of applications from healthcare products to mold making for mechanical properties. This grade is a low viscosity as well as high purity thermostat elastomer which maintains its natural properties over a huge range of temperatures.

Liquid silicone rubber (LSR) has a huge number of benefits that make it perfect for a huge range of applications. It has incredible heat resistance that also helps it to have brilliant low-temperature flexibility to around -50°c. LSRs also have very low compression sets in the range of around 15%-20%.

RTV Silicone Rubber


RTV Silicone is a two-part silicone rubber that is used to create flexible silicone moulds for castings. It is made from one part RTV-1 or two components RTV-2 with a hardness range from very soft to medium. The grade also has very low shrinkage as well as the impressive temperature range of most other silicone grades.


VFR(2) is a flame retardant grade of silicone developed for rail applications. It is available in 68° Shore A, pigmentation is limited to shades of grey. This material meets the following rail spec:



BS EN ISO 4589-3 1996

NF F 16-101 & NF F 16-102 Classification: F0

Learn more about rail applications of silicone rubber.

VFR 203-803

This flame-retardant grade of material is specified for use in aerospace applications and is available from 20° shore A to 80° shore A. Its natural colour is off-white and pigmentation is limited to shades of grey and some other colours. This material meets the following FAR/JAR specifications:

F1 Flammability CS 25.853 (a) Amdt.18 App.F Pt.I(a)(1)(i) & (b)(4) 60s Vert.

F3 Flammability CS 25.853 (a) Amdt.10 App.F Pt.I(a)(1)(v) & (b)(5) 15s Horiz

F5 Flammability CS 25.853(a) Amdt.18 App.F Pt.I(a)(2)(ii) & (b)(6) 30sec/45° (60sh only)

F9 Smoke Emission ABD0031 IssF

F10 Toxic Gas Emission ABD0031 (ppm) IddF

Learn more about silicone rubber in aerospace.

Silicone Sponge

Silicone sponge is available in a range of densities and colours. Specialised food safe and flame-retardant grades are available.

Learn more about silicone sponge products from Viking Extrusions.

Metal detectable Silicone Rubber


Metal detectable grades of silicone contain metal filings in them and are widely used in the food industry. These filings allow for easy detection if material breaks away from the seal. Metal detectable grades are available from 45° Shore A to 75° Shore A in blue.

Steam Resistant Silicones


This is a high-quality compound that has been developed specifically to resist high-pressure steam applications. It has an operating temperature from -60°C to +260°C and is available at 60° shore A.

Conductive Silicones

Semi-conductive silicone has a low volume resistivity after high-temperature exposure and is available in black 75° Shore A.

For more information on any of our available compounds please contact one of our technical advisors.

 Check our range of silicone grades on the data sheet.

Get in touch with Viking Extrusions

Contact our expert team of silicone engineers for advice, quotations or any other queries.

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