For sealing expansion joints, precast panels, window glazing, and bridge construction, Open Cell Backing Rod - Round acts as a critical bond breaker to prevent three-sided sealant adhesion. Its open-cell structure accelerates sealant curing by allowing the joint to breathe and cure from both sides, while its non-gassing polyurethane composition eliminates the risk of outgassing bubbles in the sealant layer.
This backing rod is extruded from medium-density, firm orange polyurethane foam. Because the cell structure is open, air and moisture pass through the backing rod to reach the rear of the sealant, initiating a faster, more uniform cure. The open-cell structure also means the rod is highly compressible and can be installed rapidly with any tool without risk of surface-puncture outgassing. If the foam is compressed or nicked during installation, it will not release gas bubbles into the curing sealant. Its low surface strength and shearing capabilities ensure that sealants subjected to dynamic joint movement are not restricted by backing rod adhesion.
Suitable for both internal and external applications on the following substrates:
The backing rod is compatible with cold-applied acrylic, silicone, polyurethane, MS, SPUR, and hybrid sealants. It is also compatible with hot-pour sealants, including silicone, rubber, and asphalt, within specified temperature limits.
Most sealants require a 2:1 width-to-depth ratio. When correctly installed, the backing rod controls the tooling depth so the sealant thickness is half its width. Use of the Backing Rod Insertion Tool (TOOLBACKROD) is recommended to set the backing rod to the correct, consistent depth. If the joint depth is too shallow to accommodate a backing rod, use a bond breaker tape instead to prevent three-sided adhesion.
To ensure proper compression in round joints, select the rod size according to the joint width limits below:
Choose open-cell backing rod to prevent sealant gassing and allow two-sided curing. Its breathable structure eliminates solvent entrapment that causes bubbling, which is a common issue with closed-cell rods.
Yes, it is compatible with most cold-applied sealants including Acrylic, Silicone, PU, MS, SPUR, and Hybrid types. It also works with hot pour sealants such as silicone, rubber, and asphalt. For sealants applied above +70°C, consult our Technical Department.
Yes, the open-cell structure allows sealants to cure from both sides, which leads to a faster and more consistent cure. This breathable design prevents common cure problems associated with non-breathable backing materials.
No, it is not recommended for internal swimming pool applications or areas with high chlorine exposure above 5 ppm. These conditions can compromise the material's integrity over time.
| Application | Key benefit | Primary trades |
|---|---|---|
| Expansion joints in concrete and masonry | Prevents three-sided adhesion, allowing sealants to move freely and reducing premature failure. Ensures correct sealant depth for optimal performance. | Civil contractors, concreters, masons |
| Window glazing and precast panel joints | Promotes faster, more complete sealant cure by allowing vapour escape, preventing gassing and bubbles. Maintains sealant integrity in dynamic joints. | Glaziers, precast installers, facade contractors |
| Behind various cold-applied sealants (Acrylic, Silicone, PU, MS, SPUR, Hybrid) | Acts as a non-gassing bond breaker, crucial for sealants that release solvents or moisture during cure. Supports a wide range of sealant chemistries. | Caulkers, waterproofers, general builders |
| Behind hot pour sealants (silicone, rubber, asphalt) | Compatible with high-temperature applications up to 70ºC (and intermittently up to 260ºC) ensuring performance in demanding environments. | Road maintenance, civil construction |
Store in a cool, dry place between 10ºC and 35ºC, away from direct sunlight. When stored as recommended, the product has a shelf life of 5 years.
Adheseal Open Cell Backing Rod does not require specific surface preparation itself. However, proper preparation of the substrate is critical for the sealant's performance, which is applied over the backing rod.
Surface prep: Ensure the joint is clean, dry, and free of contaminants before installing the backing rod. The sealant's specific TDS will detail full surface preparation requirements for optimal adhesion and performance.
Primer: Not required for the backing rod. Primer requirements depend entirely on the sealant being used and the substrate it is applied to. Refer to the specific sealant's technical data sheet for primer recommendations.
| Property | Value |
|---|---|
| Product Type | Polyurethane Foam |
| Density | 32 ± 3.0 Kg/m³ |
| Tensile Strength | 120 < kPa |
| Compression Set | 10 > % |
| Indentation Force Deflection 25 Percent | 340 ± 20 N |
| Elongation | 90 < % |
| Ball Rebound | 50 > % |
| Application Temperature | -40°C to +70°C |
| Service Temperature | -60ºC to intermittent 260ºC |
| Chemical Resistance | Excellent to water, detergent solutions, Moderate diluted acids & alkalis, petrol & oil for short periods |
| Compressibility | 25% nominal at 70 to 100 gms/sq-cm |
| Approximate Density | 64 to 96 kg per cubic meter |
| Shelf Life | 5 years |
Here are some common examples on where Open Cell Backing Rod - Round used by our customers.
