What is denatured alcohol?

Hardware stores sell denatured alcohol as a cleaner, a fuel, or a solvent. What does denatured mean? What’s the difference between denatured and other alcohol, such as what you find at a drug store, or the liquor store?

Denatured alcohol is ethanol, sometimes as little as 50 percent by volume, mixed with other chemicals to make it undrinkable. It has an unpleasant smell and taste, and drinking it can cause nausea, blindness, or even death.

Measures To Prevent The Illegal Manufacture Of Alcohol

The main ingredient in denatured alcohol is ethyl alcohol, or ethanol. Some people also call ethanol grain alcohol or drinking alcohol. Two well-known alcoholic drinks contain ethyl alcohol. Everclear is 95% ethyl alcohol. Vodka is typically 40% ethyl alcohol.

Many countries impose heavy taxes on alcoholic beverages for public health policy purposes. But alcohol has many uses beyond just drinking. It is a useful cleaner, industrial solvent, or fuel. The problem is that if governments allowed stores to sell pure ethanol for these purposes, people could buy it for consumption and dodge the tax.

The compromise is to denature the alcohol. The process adds additional chemicals to the ethyl alcohol to make it taste and smell bad, and cause nausea or even death. The exact chemical mix varies. But another reason for the specific choices is to make it difficult or impossible to distill the additional chemicals out.

The additional chemicals range from isopropyl alcohol, methanol, and even MEK, a nasty industrial solvent frequently sold as lacquer thinner or plastic model welder.

Since people cannot drink it safely, hardware stores and other stores can sell it without a liquor license. It also has no additional taxes other than regular sales tax. The writing on the tin often touts its properties as a a streak-free glass cleaner or camping fuel. Model railroad hobbyists will use it for cleaning their model train track, for two reasons. It’s cheaper than rubbing alcohol. They also believe it doesn’t contain water. But that’s only true of 200 proof.

Isopropyl, or rubbing alcohol, is not safe to drink. That is why drugstores can sell it without a liquor license, and you don’t need ID to buy it. Since it’s one of the ingredients used to denature ethanol, there is no need to denature it any further.


what is denatured alcohol
Hardware stores and paint stores can sell denatured alcohol as a cleaner or solvent because it is not safe to drink.

When drinking alcohol is prohibited, denatured alcohol is sometimes consumed recreationally. For example, during a 3-day period in December 1926, 31 people in New York City died of methanol poisoning from drinking denatured alcohol.

This resulted in changes to the formulation, adding a chemical to make the alcohol bitter, other substances to give it an unpleasant chemical odor, and agents to induce vomiting.

New Zealand is one notable country that does not permit methanol or methyl alcohol in denatured alcohol due to the risk of death.

Denatured alcohol is safe to use as a cleaner, solvent, or fuel. It’s just not safe to drink, and it’s best not to breathe its fumes. Not that you would want to.

The effects of methyl alcohol specifically

Methyl alcohol can and does occur in drinking alcohol, and is one reason why cheap liquor causes worse hangovers than costlier liquor. The process is generally to let the alcohol sit, so the methyl alcohol settles on the bottom. Skimming the drinkable alcohol off the top is a more difficult and costly process and it lets some drinkable alcohol go to waste. That’s one reason pricier liquors cost more. But the percentage of methanol in hardware store alcohol is much higher than the percentage in the house brand vodka you find at such fine establishments as Dirt Cheap Cigarettes, Beer, and Liquor. The methyl alcohol content in moonshine was also what causes blindness or paralysis.

It only takes 10 mL of methanol to cause permanent blindness. As little as 30 mL can be fatal, but a fatal dose is usually closer to 100 mL. Not knowing the percentage of methyl alcohol in any given denatured alcohol, it’s impossible to know how much someone can drink without causing blindness or other ill effects.

What does denatured alcohol smell like?

Denatured alcohol has a strong chemical scent that is unpleasant. Exactly what it smells like depends on what was added to it. But unlike grain alcohol, which is known for not having a strong smell, denatured alcohol has an unpleasant odor, designed to warn you of what it is.

Measuring alcohol content

While drugstore alcohol is labeled with a percentage indicating its purity, denatured alcohol and alcohol for consumption are both measured by proof. Proof is double the percentage. That means 200 proof alcohol is 100% alcohol. 100 proof alcohol by contrast is only 50%.

200 proof denatured alcohol is 100% alcohol. It just means that the additives are poisonous alcohols such as methyl alcohol (methanol) and/or isopropyl alcohol (IPA).

190 proof denatured alcohol is 95% alcohol, but has other non-alcoholic additives to denature it.

If the package does not list proof at all, it is likely to be no more than 100 proof, or 50% alcohol. It can be less.

The remaining percentage can be almost anything. Some percentage of it will be ingredients to make it taste and smell bad and make you sick.It may also contain some dye to make it visually clear what it is, to distinguish it from drinking alcohol. But a large percentage of the rest will be water, since water is cheap and somewhat inert. The additives don’t change the properties of the alcohol as a solvent, cleaner, or fuel. They also don’t change the molecular structure at all. They just make it unsafe or unpleasant for human consumption.

Is all 190 proof alcohol denatured?

Any 190 proof alcohol that comes from someplace other than a liquor store is denatured. If it didn’t come from a liquor store, smells bad, and you don’t need ID to buy it, it’s not safe to drink. It’s a cleaner or a fuel. Drinking it will make you sick, or worse.

It’s also better not to use it for first aid. While isopropyl alcohol is also not safe to drink, it has a lower toxicity. Methyl alcohol can seep into your skin and damage it, which makes it a liability for first aid. While some hand sanitizer contains it, that hasn’t always been permitted by law.

If you need to treat an injury, use rubbing alcohol or hydrogen peroxide if at all possible.

Denatured Alcohol in the U.S., U.K. And Europe

Denatured alcohol goes by many names depending on the region. The UK and most other English-speaking countries like Australia, Canada, Ireland, New Zealand, and South Africa call it methylated spirits, since the primary additive is methyl alcohol. However, New Zealand no longer permits use of methyl alcohol, though it continues to use the name. In Europe, it may be called wood spirit, or denatured rectified spirit.

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4 thoughts on “What is denatured alcohol?

  • October 26, 2021 at 8:59 am

    Most vodka is 80 proof, which is 40% ethanol, not 80%. 100 proof vodka (50% ethanol) is also readily available. Vodkas with a higher percentage of ethanol are made, all the way up to Polish-made Spirytus which is 192 proof (96% ethanol).

    High percentage ethanol that is not denatured is made for laboratory use; denatured alcohol is not suitable for many experiments because the denaturing ingredients will ruin the results. It is not available for retail purchase in the US; you have to prove that you’re a legitimate research facility to buy it. The most common is 95%, and it can be bought in large drums. 100% ethanol is also made, but it requires special handling and only comes in small packages because ethanol is hygroscopic; in other words, it will absorb water from the atmosphere if left out, quickly reducing to about 95% ethanol. At one time it was common for students at engineering schools to “liberate” some of the 95% ethanol from labs to drink; it’s essentially identical to Everclear so it’s equally safe or unsafe. The schools may be controlling access to it more carefully now.

  • October 27, 2021 at 9:42 pm

    60 years ago my mother was able to buy me a small (4 oz?) bottle of 95% alcohol for chemistry experiments from the local pharmacist, I expect that would be difficult now.

    • October 28, 2021 at 4:31 pm

      My dad did the same for me, maybe 30 years ago. I think the only reason he could was because he was a doctor. I’d completely forgotten about that.

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