Sponge Cord (Expanded Neoprene)
Expanded neoprene sponge cord is supplied by the metre in a selection of diameters. As a soft compressible material, it is ideal for creating watertight seals, joining into o rings, or making other custom sized gaskets. The ends can be joined together using good quality superglue or contact adhesive.
Manufactured from closed-cell materials, our sponge cord does not absorb water so can be used for making a watertight seal on boat hatches, lockers, car boots, enclosures, and cabinets. Expanded neoprene is also a soft and compressible material that has excellent a resistance to temperature, UV, air and ozone. This makes it suitable for use in outdoor environments that may subject the seal to extreme temperatures or weather conditions.
Sponge cord has also historically been used in replacement of Crittall glazing seals and baco glazing seals on metal greenhouses. As a material suitable for sealing, insulation and vibration dampening, it can reliably be used to cushion the glass against the aluminium frame.
All Sponge SealsFrequently Asked Questions
What is expanded neoprene sponge cord used for?
Expanded neoprene sponge cord is a soft, flexible and compressible sealing material commonly used to create custom gaskets, O-rings, and edge seals. Because it compresses easily and returns to its original shape, it forms an effective barrier against air, dust and water.
It is widely used in marine, automotive, industrial and domestic applications, including sealing boat hatches, vehicle boots, lockers, cabinets and enclosures. Its cushioning properties also make it useful for vibration dampening and for protecting components from impact or movement.
Can this sponge cord be used to make watertight seals?
Yes. Expanded neoprene sponge cord is manufactured from a closed-cell material, meaning it does not readily absorb water. When compressed correctly, it forms a reliable watertight seal suitable for use on boat hatches, lockers, control cabinets, outdoor enclosures, and other applications where moisture protection is essential.
Its resistance to UV, weathering, and temperature changes further supports long-term sealing performance in outdoor or marine environments.
How do I join the ends together to create an O-ring?
To create a continuous O-ring or loop, simply cut the cord cleanly and join the ends using a good-quality superglue or contact adhesive suitable for rubber. Apply a thin, even layer of adhesive to both mating surfaces, press them firmly together and allow the joint to cure fully before installation.
For best results, ensure the cuts are square and the surfaces are clean and dry. A sharp craft knife or guillotine cutter will give the straightest cut. This will help the O-ring seal more consistently.
Which adhesive should I use for bonding sponge cord?
We recommend using a rubber-compatible superglue for quick, clean bonding or a contact adhesive for a more flexible joint. Both create strong seals when used correctly, but superglue is preferred for small, precise O-ring joins, while contact adhesive can be better for larger bonding areas or more challenging installations.
Whichever adhesive you choose, it is imperative to ensure that all surfaces are clean and free from dust, oils or contaminants to maximise bond strength.
Is expanded neoprene sponge cord suitable for outdoor environments?
Yes. Expanded neoprene has excellent resistance to UV, ozone, air and weathering. This makes it an ideal material for long-term outdoor installations. It performs reliably even when exposed to sunlight, rain and fluctuating temperatures, retaining its flexibility and sealing ability over time.
Its durability makes it especially suitable for marine applications, outdoor cabinets, greenhouses, vehicles and any environment subject to challenging weather conditions.
Does this sponge cord absorb water?
No. The cord is manufactured from a closed-cell neoprene sponge which means the cells are sealed rather than interconnected. This structure prevents water from being absorbed into the material and allows it to maintain buoyancy and sealing performance even in wet or exposed conditions.
Because of this, it is commonly chosen for marine hatches, lockers, and outdoor equipment where water resistance is essential.
What diameters is the sponge cord available in?
Expanded neoprene sponge cord is supplied in a range of diameters to suit different sealing and gasket requirements. Common sizes typically include small diameters for precision O-rings through to larger profiles for heavy-duty sealing or cushioning applications.
All diameters are sold by the metre, allowing you to order exactly the length you need and cut or join it to create custom-sized seals.
We stock cord from 3mm diameter up to 25mm diameter.
How compressible is neoprene sponge cord, and what level of compression is recommended?
Neoprene sponge cord is designed to be soft and highly compressible, allowing it to deform easily and create an efficient seal even under low clamping pressure. Its resilience means it will spring back after compression without losing shape.
For most sealing applications, a compression of 30% of the original diameter is ideal. This provides the best balance between sealing performance and long-term durability. Excessive compression beyond 50% may reduce recovery and shorten the lifespan of the seal.
How durable is neoprene sponge cord when used in long-term installations?
Expanded neoprene is known for its excellent long-term durability. It resists UV exposure, ozone, moisture, and general weathering, enabling it to perform reliably outdoors for many years without significant degradation. Its closed-cell construction prevents water absorption, helping the seal maintain its structure and performance even in wet conditions.
Additionally, neoprene maintains flexibility over a wide temperature range and has good resistance to physical wear, making it a dependable choice for both static and moving applications. Whether used in marine environments, vehicle seals, or outdoor enclosures, it offers a long service life with minimal maintenance.