- Increased use of water results in higher reaction exotherm, which is the cause of fire
- System viscosity is high, so flowability of foaming systems in the mold is bad
- In two component-rigid foam systems, mixing ratios become high, so mixing efficiency gets lower
- System costs are high because using water, consumes high amounts of costly polyisocyanates
- Most flexible foams are now produced by using water as sole blowing agent. Otherchemical blowing agents include enolizable organic compounds like nitroalkane, aldoxime, nitrourea, acid amide, active methylene compounds as well as boric acid.