There are several ways ethanol is denatured.
Methanol as a DenaturantDenatured alcohol that is intended for use as a fuel or solvent typically contains 5% or more methanol. Another term for this type of denatured alcohol is "methylated spirits." Methanol is flammable and has a boiling point close to that of ethanol. Methanol is absorbed across the skin and is highly toxic, so it is not recommended to use denatured alcohol for making perfume or bath products unless you know the denaturant is not methanol.
Denatured Alcohol for Cosmetics and LabsDenatured alcohol for use in cosmetics often contains water and a bittering agent (Bitrex or Aversion which are denatonium benzoate or denatonium saccharide), but other chemicals are sometimes used. Other common additives include (but are not limited to) isopropanol, methyl ethyl ketone, methyl isobutyl ketone, pyridine, benzene, diethyl phthalate, and naphtha.
Color of Denatured AlcoholIn the United States, denatured alcohol usually is colorless. In some countries, denatured alcohol must be colored blue or purple using an aniline dye, in order to distinguish it from consumption-grade ethanol.
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