Butanone, also known as methyl ethyl ketone, is an organic compound and is a colorless transparent liquid. It is mainly used as a solvent for paints and inks, as a binder for dyes, as a dewaxing agent for lubricating oils, as a vulcanization accelerator, and as an intermediate for the preparation of medicines, dyes, detergents, fragrances, and certain catalysts.

MEK is a highly flammable liquid and vapor/air mixtures are explosive. When people inhale methyl ethyl ketone, symptoms such as cough, headache, dizziness, nausea, vomiting, drowsiness, numbness, and difficulty breathing will appear. Eye contact may cause redness and pain. Symptoms of dry skin may occur upon skin contact.