Gorilla MS Expanding Foam is the first ”isocyanate free” expanding foam in the world! It is great for filling cavities, mounting and sealing of windows and doorframes, creation of a soundproof screen. Gorilla MS Foam utilizes a moisture-curing system and performs best on moderately wet, porous surfaces (wood, concrete, stone). On non-porous surfaces, the best performance is achieved when the surface is almost dry and when the joint/cavity is not deep (max. 7.5 cm). In the case of a deeper joint/cavity, it is better to fill the gap in two sessions, with a drying/curing time in between.