Stratathane ST-520 1 Gallon


  • A two-stage reaction takes place when ST-520 comes in contact with water. The mixture first expands and thickens.
  • As it cures, ST-520 quickly solidifies into a strong impermeable water barrier in just minutes.
  • Hydrophyilic ST-520 foam expands up to ten times its starting volume.
  • A dense material is preferred for most applications.
  • Greater density is obtained by controlling grout placed relative to void space and static head pressure.
  • ST-520 is rated high in its ability to tolerate freeze-thaw, wet-dry cycling, extrusion, and compression.


Technical Data Sheet

Safety Data Sheet

4 in stock

The ST-520 Poly-Foam Injection Resin by Stratathane is a cutting-edge hydrophilic wonder, meticulously crafted to offer an unmatched solution for sealing leaks in concrete and masonry structures. Crafted with precision and innovation, ST-520 is a single-component, flexible polyurethane resin that redefines leak-sealing technology.

Hydrophilic Marvel: ST-520 is a hydrophilic champion, engineered to interact with water in a transformative manner. Upon contact, it sets off a remarkable expansion process, filling voids and gaps with an adaptable closed-cell foam. This expansion seals leaks while maintaining the flexibility to accommodate structural movements and stresses.

Innovative Composition: ST-520’s secret lies in its ingenious composition. Formulated with a base of TDI, this polyurethane resin boasts a 15% infusion of acetone. Not only does acetone contribute to a slight and pleasant solvent-like fragrance, but it also enhances the resin’s viscosity, ensuring the optimal distribution of water throughout the mixture.

Cure Without Compromise: Say goodbye to worries about toxicity. ST-520, once cured, boasts an essentially non-toxic nature. It forms an elastic and robust seal that staunchly halts water intrusion while offering the resilience to withstand crack movements. This feature safeguards against stress transfer, ensuring the longevity of your structure.

Swift and Efficient: Time is of the essence, and ST-520 respects that. At approximately 70°F, this incredible resin undergoes a rapid 30-second reaction upon contact with water, followed by an efficient two-minute cure time. Its expedited cure cycle allows for speedy project completion, a testament to its unmatched performance.

Innovative Reaction Mechanism: ST-520 showcases a two-stage reaction mechanism that sets it apart. As it encounters water, it initially expands and thickens, filling every nook and cranny. Subsequently, it solidifies into a formidable water barrier within minutes, safeguarding your structures from unwanted moisture intrusion.

Density and Durability: ST-520’s versatility is further highlighted by its variable density properties. While it can expand up to ten times its original volume, for most applications, a denser material is preferred. Achieving this density is a breeze – simply control the grout placement in relation to the void space and static head pressure.

Defying the Elements: ST-520 stands resilient against the elements. Its exceptional tolerance for freeze-thaw cycles, wet-dry fluctuations, extrusion, and compression make it an all-weather performer. Whether facing the harsh cold or the scorching sun, ST-520 remains steadfast in its mission to preserve the integrity of your structures.

Revolutionize your leak-sealing endeavors with the ST-520 Poly-Foam Injection Resin. From its hydrophilic prowess to its swift and efficient cure, it’s the ultimate partner in safeguarding concrete and masonry structures. Trust Stratathane’s innovation to redefine the future of leak solutions. Your structures deserve nothing less than the best – ST-520 is here to deliver.


Need more Stratathane ST-520? See the 5 gallon version here!

Weight 10 lbs
Dimensions 9 × 9 × 9 in