Acetone (propan-2-one)
Fast, strong and VOC-exempt under US EPA rules: acetone is the go-to cleanup solvent and a key ingredient in many low-VOC formulas, but it is extremely flammable.
Acetone (propan-2-one) is the simplest ketone, a clear liquid that boils at 56 °C and evaporates very quickly. Its flash point is about −20 °C, so it can form ignitable vapor even in cold weather.
Acetone is used for equipment and tool cleanup, surface wipe-downs, and as a fast solvent in lacquers, adhesives and some low-VOC coatings. Because US EPA exempts it from VOC calculations, formulators use it to adjust viscosity without raising regulated VOC content.
A strong polar solvent, acetone dissolves many resins and uncured coatings. Its very fast evaporation can cause blushing (moisture condensing on the cooling film) and dry spray if overused. It has no hydroxyl group, but commercial grades can hold water, so use dry grades with isocyanates.
Extremely flammable: eliminate ignition sources, ground and bond containers and ventilate. Vapors can cause drowsiness and dizziness; it also dries and irritates skin.
Many applicators use it for cleanup, but check the equipment and material manufacturers’ recommendations, and remember its extreme flammability around hot equipment.
US EPA found it has negligible photochemical reactivity in forming ozone and exempted it from the VOC definition in 1995.
