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What’s the difference between denatured alcohol vs. isopropyl alcohol? Are they different names for the same thing? Or does each one have its own uses?

While there is some overlap between denatured and isopropyl alcohol, there are very important differences in their makeup and usage. In this post, we’ll define what each one is and what it’s usually used for. We’ll also talk about how to use both isopropyl and denatured alcohol safely.

But first, let’s clear up some confusion around the term ‘alcohol.’

Not All Alcohols Are the Same

If you ask a scientist what alcohol is, you’ll probably get a different response than if you asked a layperson. From Sciencing.com, we get this answer: “In common usage, ‘alcohol’ means ethanol – the drinkable, mind-altering substance found in vodka and beer. However, in chemistry, ‘alcohol’ refers to a hydroxyl group, consisting of hydrogen bonded to oxygen, attached to a carbon group.” 

So, in everyday terms, not all alcohols are the kind of alcohol that can or should be consumed. Some of it, as we’ll see, shouldn’t even be applied to the skin.

What Is Isopropyl Alcohol?

First up, let’s take the familiar isopropyl alcohol. What is it? According to Wikipedia:

“Isopropyl alcohol is a colorless, flammable chemical compound with a strong odor. As an isopropyl group linked to a hydroxyl group, it is the simplest example of a secondary alcohol, where the alcohol carbon atom is attached to two other carbon atoms. [..] It is primarily produced by combining water and propene in a hydration reaction or by hydrogenating acetone.” 

Isopropyl alcohol is commonly found in pharmacies and groceries stores, where it’s sold as an antiseptic or cleaning agent. Industrially, it’s also an ingredient in many solvents, cleaners, and fuel additives.

Are Rubbing Alcohol and Isopropyl Alcohol the Same?

Rubbing alcohol is also widely available and used as an antiseptic. It can be a diluted form of isopropyl alcohol or ethyl alcohol. (The “rubbing” in rubbing alcohol comes from its former use in massage treatments.)

What Is Ethyl Alcohol?

Ethyl alcohol is a very wide category. It’s what’s known as a primary alcohol – a group that includes beer, wine, spirits, and other human-consumable alcohols, as well as all alcohols made by fermenting sugars. You can also make ethyl alcohol in a lab by ethylene hydration and other processes. 

You may have heard of using ethyl alcohol as a fuel – it’s known as ethanol. When mixed with gasoline, it becomes E85 or flex fuel. 

Even though they belong in the same family as other ethyl alcohols, the drinkable alcohols of beer, whiskey, etc. are less toxic than the other things we call ‘alcohol.’ That’s why is not a good idea to drink isopropyl alcohol.

What Is Denatured Alcohol?

Now that we’re familiar with the main branches of the alcohol family tree, what is denatured alcohol? Wikipedia defines it as “ethanol that has additives to make it poisonous, bad-tasting, foul-smelling, or nauseating to discourage its recreational consumption. It is sometimes dyed so that it can be identified visually.” 

The ethyl alcohol in denatured alcohol isn’t lethal per se; however, because it’s a very strong concentration of alcohol, denatured alcohol can be highly toxic. (Severe illness, organ failure, blindness, and death are known side effects of consuming very strong alcohol.) Because it’s not intended for human consumption, nasty flavors and smells are added to denatured alcohol. The alcohol could still function for most uses outside of certain types of medical and lab work, but it would be much less appealing to anyone who wanted to drink it as a beverage.

Uses of Denatured Alcohol vs. Isopropyl Alcohol

In summary, isopropyl alcohol is a secondary alcohol that has not been treated with additives (with the exception of water). Denatured alcohol is primary alcohol mixed with additives to make it unpalatable and, in some cases, even more toxic. (Get a detailed explanation of primary, secondary, and tertiary alcohols here. ) How might either of these alcohols be used?

  • As a cleaning agent: If you’re cleaning electronics, use isopropyl alcohol; it evaporates quickly and cleanly because there are no additives. Denatured alcohol’s extra ingredients may leave damaging residue. Outside of electronics, denatured alcohol makes a great grease remover.
  • As a solvent: Both can be used successfully as solvents: purer isopropyl alcohol is usually used for lab and medical work, while stronger denatured alcohol is used for industrial applications. 
  • As a disinfectant: In medical settings, isopropyl alcohol is often used to disinfect wounds, surfaces, hands, and medical equipment; such small amounts can be absorbed into the body with no harm. Denatured alcohol should be avoided because of the risk of ingestion. Also, its toxic additives can be absorbed through the skin.

Denatured and Isopropyl Alcohol: Safety Precautions

If you’re working with denatured alcohol or isopropyl alcohol – even with the standard household isopropyl alcohol concentration of 60-70 percent – take the following safety precautions:

  • Use personal protective equipment (impermeable gloves, eye protection, respiratory protection, etc.) to avoid unnecessary exposure.
  • Avoid sparks and open flames. Both isopropyl alcohol and denatured alcohol are very flammable.
  • Make sure there is plenty of ventilation in the area you’ll be working.
  • Avoid inhaling the fumes. If you feel dizzy, sick, or wheezy, move to fresh air.
  • Avoid contact with skin and eyes. 
  • Do not ingest or drink either product.
  • Do not smoke, eat, or drink xwhile working with an isopropyl alcohol or denatured alcohol product.
  • Properly close containers and store them in a cool, well-ventilated place away from other chemicals, sparks, flames, and excessive heat. 

Denatured Alcohol vs. Isopropyl Alcohol: Similar, But Very Different

While denatured alcohol and isopropyl alcohol have similar uses and are superficially the same (in that they’re both termed alcohols), they are in fact quite different:

  • Denatured alcohol is ethyl alcohol to which foul-smelling and bad-tasting elements have been added. Some of these additives are toxic. And while ethyl alcohol itself isn’t poisonous in weaker concentrations, the high concentrations present in denatured alcohol can be very harmful to humans and animals. It’s often used in strong solvents and industrial applications.
  • Isopropyl alcohol is not a simple ethyl alcohol; it’s a secondary alcohol that’s produced in a different way. Although it can be safely used externally in small amounts (i.e. as a hand sanitizer), isopropyl alcohol is toxic and shouldn’t be ingested. Unlike denatured alcohol, isopropyl alcohol doesn’t usually have anything other than water added to it. Because it doesn’t have any additives, it’s better suited for some medical and lab work. It’s also better as an on-the-body antiseptic, as denatured alcohol’s additives can cause unwanted side effects.

Of course, your choice of isopropyl alcohol or denatured alcohol will depend on what you need it for. But now that you have the basic knowledge of these alcohols’ uses and differences, you can have a better idea of which one will meet your needs.