Denatured alcohol

Polish denatured alcohol

Australian methylated spirits

Denatured alcohol or methylated spirits is ethanol that has additives to make it more poisonous or unpalatable, and thus, undrinkable. In some cases it is also dyed.

Denatured alcohol is used as a solvent and as fuel for spirit burners and camping stoves. Because of the diversity of industrial uses for denatured alcohol, hundreds of additives and denaturing methods have been used. Traditionally, the main additive is 10% methanol, giving rise to the term "methylated spirit." Other typical additives include isopropyl alcohol, acetone, methyl ethyl ketone, methyl isobutyl ketone, and denatonium.^[1]

Denaturing alcohol does not chemically alter the ethanol molecule. Rather, the ethanol is mixed with other chemicals to form an undrinkable solution.

Different additives are used to make it difficult to use distillation or other simple processes to reverse the denaturation. Methanol is commonly used both because of its boiling point being close to that of ethanol and because it is toxic. In many countries, it is also required that denatured alcohol be dyed blue or purple with an aniline dye.

Purpose

Denatured alcohol is not, in itself, a preferred product—that is, it is not something which would be normally demanded if given the alternative of normal ethanol. Denatured alcohol and its manufacture are a public policy compromise. The supply and demand for denatured alcohol arises from the fact that normal alcohol (which in everyday language refers specifically to ethanol, suitable for human consumption as a drink) is usually very expensive compared to similar chemicals, being highly taxed for revenue and public health policy purposes (see sin tax). Pure ethanol would have the same health hazards as any other high concentration alcohol. As a result, if pure ethanol were made cheaply available as a fuel or solvent, people would drink it.

Denatured alcohol provides a solution to permit legitimate use and manufacture of ethanol, whereby cheap ethanol can be made available for non-consumption use without the risk of it being converted for consumption. The process creates an ethanol-containing solution that is not suitable for drinking, but is otherwise similar to ethanol for most purposes. As a result there is no duty on denatured alcohol in most countries, making it considerably cheaper than pure ethanol. Consequently, its composition is tightly defined by government regulations which vary between countries.

Formulations

There are several grades of denatured alcohol, but the denaturants used are generally similar. As an example, the formulation for completely denatured alcohol, according to British regulations must be:^[2]

Completely denatured alcohol must be made in accordance with the following formulation: with every 90 parts by volume of alcohol mix 9.5 parts by volume of wood naphtha or a substitute for wood naphtha and 0.5 parts by volume of crude pyridine, and to the resulting mixture add mineral naphtha (petroleum oil) in the proportion of 3.75 litres to every 1000 litres of the mixture and synthetic organic dyestuff (methyl violet) in the proportion of 1.5 grams to every 1000 litres of the mixture.

Uses

Denatured alcohol has a variety of common uses:

• As a fuel for marine and ultra-light camping (backpacking) stoves. It is inexpensive, may be extinguished with water, and can be transported without special containers. However, safety concerns do arise from the near-colourless flame with which alcohol burns. A jellied and dyed form is used in the Sterno brand fuel "Canned Heat", and is meant to be ignited and used in the container.
• To pre-heat the vaporizing tubes on a wickless paraffin stove such as a Primus stove
• As a sanding aid, as the alcohol helps to more easily remove excess dust because it does not open the wood grain the way that water does.^[3]
• As a mealybug exterminator.^[4]
• As a cleaning aid in removing ink stains from upholstery or clothes.
• As a cleaner in daily housekeeping
• To disinfect skin prior to an injection or minor surgery, such as draining a blister (also see rubbing alcohol).
• It is often used as an antiseptic for minor wounds, although this practice is harmful and counterproductive, since it kills skin cells, and the dead tissue provides a food source for bacteria (since the wound will not remain completely sterile).^{[citation needed]}
• As a solvent in shellac and shellac-based products.
• As an excipient in a number of pharmaceutical products for oral and topical use.^[5]
• As a less expensive alternative to pure ethanol in preserving biological specimens.
• As a less toxic alternative to methanol in the production of biodiesel fuel. Biodiesel produced using ethanol is properly called fatty acid ethyl ester, whereas biodiesel from methanol is properly referred to as fatty acid methyl ester.^[6]
• As a germicide in the removal of fungus from skin and coldsore treatment.
• For maintenance of wicks in kerosene heaters and lamps to remove water contaminants and restore the capillary action of the wick. As a wick cleaner and a kerosene additive, adding approx. 1 teaspoon denatured alcohol per gallon of kerosene.
• As a fuel for older toy steam engines which used a wick type or vapourising burner.^[7]
• Window washing

In the United States, small amounts of denatured alcohol are used in many consumer products such as toothpaste where they are labeled as "SD alcohol XX", where SD stands for "specially denatured" and XX is the formula used in the denaturing process that specifies the denaturants. These formulas for denatured alcohol are found in 27 CFR part 21 of the Code of Federal Regulations.^[8] Some of these formulas, such as SD alcohol 38-B,^[9] are designed to be unpalatable but otherwise non-poisonous; they are used in applications like mouthwashes where some amount of incidental ingestion is expected. (The specific denaturants in formulas 37 and 38-B closely resemble the active ingredients in alcohol-based mouthwashes like Listerine.^[10])

Consumption and toxicity

See also: Harm reduction

Despite its poisonous nature, denatured alcohol is sometimes consumed as a surrogate alcohol, which can result in blindness or death if the denatured alcohol contains methanol. This happened during Prohibition, when the U.S. government used methanol in industrial alcohols manufactured in the United States.^[11] To help prevent this, denatonium is often added to give the substance an extremely bitter flavor. Substances such as pyridine help to give the mixture an unpleasant odor, and emetic (vomiting) agents such as syrup of ipecac may also be included. In Poland and other European countries denatured alcohol contains only substances having bitter flavor (like acetylsalicylic acid) and odour, and does not contain methanol or any substance of severe toxicity.

See also

• Rubbing alcohol
• E85

References

1. ^ "Ethanol Denaturants". The Online Distillery Network. 22 November 1993. http://www.distill.com/specs/EU2.html. 
2. ^ "The Denatured Alcohol Regulations 2005". Office of Public Sector Information. 2005. http://www.legislation.gov.uk/uksi/2005/1524/contents/made. 
3. ^ "Denatured Alcohol as a Sanding Aid". Woodzone.com. Unknown year. http://www.woodzone.com/tips/denatured.htm. Retrieved 2006-04-14. 
4. ^ "Mealy Bug Treatment and Description". Succulents.co.za. http://www.succulents.co.za/succulent-plant-pests/mealy-bug.php. Retrieved 2007-09-30. 
5. ^ FDA approved excipient database (search for "alcohol, denatured")
6. ^ "Transesterification Process to Manufacture Ethyl Ester of Rape Oil" (PDF). University of Idaho. http://journeytoforever.org/biofuel_library/EthylEsterofRapeOil.pdf. Retrieved 2008-04-01. 
7. ^ Mamod
8. ^ CFR Title 27 volume 1
9. ^ 27 C.F.R. 21.65
10. ^ SD alcohol 37 contains thymol, menthol, and eucalyptol, three of the four active ingredients in Advanced Listerine with Tartar Protection Antiseptic according to its Drug Facts label. SD alcohol 38-B allows a wide range of non-poisonous denaturants alone or in combination, including all four of Listerine's active ingredients.
11. ^ U.S. government poisoned alcohol

External links

• 27 CFR 20, regulations relating to denatured alcohol in the United States
• Specifications and licensing of methylated spirits in the United Kingdom
• European Community COMMISSION REGULATION (EC) No 3199/93 on the mutual recognition of procedures for the complete denaturing of alcohol for the purposes of exemption from excise duty Pdf