Silicone

Silicone — high‑performance sealing elastomer

Silicone belongs to a family of elastomers composed of silicon, oxygen, hydrogen and carbon. It stands out for maintaining flexibility and resisting compression set, while functioning reliably across one of the widest temperature ranges of any common sealing elastomer.

Why choose silicone for seals and gaskets

• Wide temperature tolerance — Silicone rubbers (commonly VMQ) remain flexible at low temperatures and stable at elevated ones. Specialized formulations (e.g. phenyl‑silicone, PVMQ) can perform down to –100 °C (–148 °F), and some advanced silicones survive short-term exposure to as high as ~315 °C (600 °F).
• Retained high-temperature integrity — Compared with many elastomers, silicone preserves its mechanical and sealing properties better under heat.
• Excellent environmental and weather resistance — Silicone resists degradation from hot air, ultraviolet (UV) radiation, ozone and general outdoor exposure, making it well-suited for long-term or outdoor sealing applications.
• Cleanliness, purity and suitability for sensitive applications — Because of its stability, inertness, and ability to be produced to strict regulatory standards, silicone is common in food‑grade, medical, and pharmaceutical sealing applications.
• Customisable properties — Silicone compounds can be formulated with different shore hardnesses, colours, and special characteristics (e.g. flame‑retardant, electrically resistant/conductive, encapsulated).

Typical Uses & Suitability

Silicone is especially well-suited for static sealing (e.g. O‑rings, gaskets, seals that do not undergo continuous movement), particularly where temperature extremes, hygiene (food/medical), or environmental exposure (UV/ozone/weather) are factors.

Given its clean, non‑toxicity and regulatory compliance potential, silicone finds frequent use in food processing, pharmaceutical manufacturing, medical devices, and other hygienic or clean‑environment applications.

Because silicone is available in different compounds and styles — including extruded cords, encapsulated O‑rings (e.g. FEP or PFA encapsulated), transparent (“clear”) grades, and US‑FDA / USP Class VI versions — it offers flexibility to meet the needs of many industries.

Choosing the Right Material for Your Application

Given the strengths and trade‑offs, silicone is typically the right choice when you need:

• Temperature extremes (very low or very high)
• Long-term environmental exposure (UV, ozone, weather)
• Clean, inert, food‑ or medical‑grade sealing
• Static sealing or low‑movement interfaces
• Customised seal types (special colours, shore hardnesses, transparent, encapsulated, etc.)

However, if you expect heavy mechanical stress, abrasion, oil or fuel exposure, aggressive chemicals, steam, or dynamic movement, it may be safer to consider alternate elastomers such as nitrile, EPDM, FKM, hydrogenated nitrile (HNBR), or perfluoroelastomer (FFKM) compounds.

Looking for an alternative style?  Click here to contact our Sales team.

Silicone compounds are not recommended for dynamic O-ring sealing applications due to relatively low tear strength and high coefficient of friction. Silicone does not perform well in concentrated acids, Fuels, Gear Oils, Ketones (MEK, Acetone) and Steam.

Please note: This Silicone Material Data Sheet section is to be used as a professional guide only. Eastern Seals (UK) Ltd may source their products from a variety of Quality Approved Suppliers and the data shown should not be relied upon by any purchaser without verification of material source.

ES REF	Colour	Temp Range	Hardness	Notes	Data Sheet
S50 FDA	RED	-55°C to 225°C	50	Food quality. Compliant to CFR 21 177-2600.	S50 FDA
S60 FDA	RED	-55°C to 225°C	60	Food quality. Compliant to CFR 21 177-2600.	S60 FDA
S60T (extruded cord)	TRANSPARENT	-55°C to 225°C	60	Food quality. Compliant to CFR 21 177-2600	S60T (extruded cord)
S60W (extruded cord)	WHITE	-55°C to 225°C	60	Food quality. Compliant to CFR 21 177-2600	S60W (extruded cord)
S70R (extruded cord)	RED	-55°C to 225°C	70	Food quality. Compliant to CFR 21 177-2600	S70R FDA
S70T (extruded cord)	TRANSPARENT	-55°C to 225°C	70	Food quality. Compliant to CFR 21 177-2600	S70T (extruded cord)
S70 FDA	RED	-55°C to 225°C	70	Food quality. Meets European Framework Regulation (EC) 1935/2004. Compliant to CFR 21 177-2600	S70R FDA
S70 WH FDA	WHITE	-55°C to 225°C	70	Food quality. Compliant to CFR 21 177-2600.	S70 WH FDA
S70	CLEAR (Transparent)	-55°C to 225°C	70	Clear (transparent) 70 shore Silicone.	S70 Clear
S70 USP Class VI	CLEAR (Transparent)	-55°C to +180°C	70	Developed to support use of this silicone rubber in pharmaceutical processing and food processing applications. Formulated using only those ingredients determined by the United States Federal Food and Drug Administration (FDA) to be in accordance with Code of Federal Regulations Title 21 (CFR21), Section 177.2600. The desirable traits of cleanliness, low odour index are exhibited by our compound so that our customers receive a silicone rubber product that leads the industry in cleanliness and purity.	S70 USP Class VI
Silicone FEP Encapsulated	RED	-60°C to +205°C Short duration: to +260°C	–	Manufactured to meet the requirements of; AS568/BS1806 tolerance specifications. Silicone core (Silicone AH3188U) of our Encapsulated ‘O’ Ring complies with Part 177 of Title 21 of the Food and Drug Administration regulations for safe use as articles or components of articles for producing, manufacturing, processing, preparing, treating, packing, transporting or holding food in accordance with FDA regulation 21.CFR.177.2600.	Silicone FEP Encapsulated
Silicone PFA Encapsulated	RED	-60◦C to +260◦C Short duration: to +300◦C	–	Manufactured to meet the requirements of; AS568/BS1806 tolerance specifications. Silicone core (Silicone AH3188U) of our Encapsulated ‘O’ Ring complies with Part 177 of Title 21 of the Food and Drug Administration regulations for safe use as articles or components of articles for producing, manufacturing, processing, preparing, treating, packing, transporting or holding food in accordance with FDA regulation 21.CFR.177.2600.	Silicone PFA Encapsulated