High-Viscosity Air-Driven Expanding Blade AgitatorAir Driven Expanding Blade Agitator Gracos new expanding blade bung mounted agitator is specifically designed to properly mix spray foam and polyurea materials and to maintain suspension. Many chemistries require agitation to properly mix materials for optimal material properties and yields. The extended center shaft ensures the lower blades reach the bottom of the drum for difficult to mix materials, including emulsions.