Polyurethanes need polar solvents. Key options include: Methylene Chloride: Effective but toxic. Dimethylformamide (DMF): Strong solvent, high boiling point, toxic. Acetone: Fast-evaporating, good for uncured foam, can cause condensation. Tetrahydrofuran (THF): Flammable, excellent solvent. N-Methyl Pyrrolidone (NMP): Safer alternative for removing cured foam. These solvents are mainly used for cleaning equipment, though cured polyurethane resists complete dissolution.