Also known as 2-Hexanone, methyl n-butyl ketone, MBK, or propyl acetone, it is a clear, colorless liquid with a sharp odor. It dissolves very easily in water, and can evaporate easily into the air as a vapor. It was used in the past in paint and paint thinner, to make other chemical substances, and to dissolve oils and waxes. It is no longer made or used in the United States because it has harmful health effects. It is formed as a waste product resulting from industrial activities such as making wood pulp and producing gas from coal, and in oil shale operations.