nt cat a-4 is a quick-acting catalyst used in the production of polyurethane foams. it is a water-based catalyst that is compatible with a variety of polyurethane systems. nt cat a-4 is also non-corrosive and non-flammable. nt cat a-4 is a popular choice for a variety of polyurethane applications, including: · soft foam · hard foam · spray foam · molding plastic...