Sponge Cord (Expanded Silicone)

Expanded silicone sponge cord is commonly used for sealing applications where a soft, compressible and temperature-resistant material is required. It is ideal for preventing water ingress around hatches, cabinets, enclosures and access panels. Its smooth outer skin and uniform profile help create reliable seals.

Because silicone offers outstanding thermal stability, the cord is especially popular in industries such as medical, pharmaceutical, food processing and high-temperature manufacturing. It can be used in continuous lengths or formed into custom-sized O-rings and gasket loops.

Yes. Expanded silicone sponge cord is manufactured from a closed-cell material so does not absorb water. When compressed correctly, it forms an effective watertight barrier which makes it suitable for use in marine, industrial and outdoor environments.

Its excellent resistance to ageing, UV, and weathering ensures that the seal maintains its performance over time, even in challenging or constantly exposed conditions.

To create a continuous O-ring, cut the silicone sponge cord cleanly using a sharp blade, then bond the ends together using a good-quality silicone sealant. Silicone-based adhesives work best because they create a strong flexible joint that withstands movement and temperature changes.

For the neatest join, ensure both ends are cut square, clean and dry before applying the sealant. Allow the adhesive to fully cure before installing or compressing the O-ring to ensure a reliable seal.

The recommended option is a silicone-based adhesive or sealant, as it bonds effectively to silicone materials and maintains flexibility over a wide temperature range. A high-quality RTV (room-temperature vulcanising) silicone sealant is typically used to join the ends when forming custom O-rings.

Other adhesive types generally do not bond well to silicone surfaces, so using a purpose-made silicone sealant ensures the strongest and longest-lasting connection.

Expanded silicone sponge cord is supplied in a selection of diameters, typically ranging from 3mm up to 25mm. This allows it to be used for both fine precision sealing tasks and larger applications where a thicker seal is required.

All diameters are sold by the metre, giving you flexibility to order the exact amount you need for your project, whether you’re installing it as a linear seal or forming it into custom-sized rings.

Expanded silicone sponge cord should generally be compressed by approximately 30% of its original diameter to achieve an effective seal. This level of compression ensures a tight barrier without overstressing the material.

Silicone sponge is slightly firmer than neoprene sponge, and over-compressing it can lead to compression set, where the material does not fully recover after pressure is released. Keeping within the recommended compression range maximises both sealing performance and product lifespan.

Yes. Expanded silicone performs exceptionally well in both extreme hot and cold environments. It has a wide operating temperature range of -60°C to +200°C, making it one of the most versatile sealing materials for temperature-sensitive applications.

This broad tolerance makes it popular in sectors such as medical, pharmaceutical, laboratory equipment and industrial machinery, where reliability across fluctuating temperatures is essential.

The main differences relate to temperature resistance, firmness and industry suitability. Expanded silicone sponge cord can withstand a much wider temperature range (-60°C to +200°C), making it ideal for high-temperature or extreme-cold environments. Expanded neoprene has good general-purpose performance but cannot match silicone’s thermal stability.

Silicone sponge is also slightly firmer than neoprene and therefore offers a different feel and compression behaviour. Neoprene is often chosen for cost-effective general sealing, while silicone is preferred for specialist applications requiring high purity, temperature tolerance, or long-term environmental resistance.