How to Use Rubbing Alcohol Safely

Heather says:

This is another post in the series on household chemicals. Rubbing alcohol is frequently recommended by frugal and green bloggers for use as household cleaner.

Rubbing alcohol a general term that most often refers to isopropanol, but can also refer to ethanol. It is very important to understand that there is a difference between ethanol and isoproponal. Ethanol is the same type of alcohol you’ll find in your liquor cabinet while isopropanol is the alcohol we’re familiar with in medical applications – the pads used to wipe your skin before receiving a shot as an example. Both can be used as a topical disinfectant -think back to all the movies where nothing but a bottle of liquor was available- and this is how the term came about (the topical application, not the movie scenes).

To keep things simple, from this point forward the rubbing alcohol referenced is the white bottle of 60% – 90% isopropanol most of us are familiar with from the pharmacy department.

Rubbing alcohol should always be used in a well ventilated area.

Isopropanol is volatile which means that it evaporates quickly, creating flammable fumes. Never use rubbing alcohol near open flames or while smoking.

Ispropanol is converted to acetone in the human body. Do not drink it, do not use in an unventilated area, do not use over large areas of skin.

To understand why rubbing alcohol is so often recommended as a household cleaning solvent, let’s dive back into high school chemistry for a moment.

There is an adage like dissolves like, this refers to two types of compounds polar and non-polar. Water is a polar compound, each V shaped H20 molecule has an area with a slightly positive charge and an area with a slightly negative charge. Compounds such as fats are non-polar and do not have these charged areas. In most cases, at least without playing chemist, you won’t get a non-polar solution to mix with a polar solution. If you want to visualize this, head into the kitchen put some water a jar and add a few tablespoons of olive oil. Close the lid and shake the heck out of it. You’ll see tiny droplets of oil suspended in the water (until they eventually float to the top) but these droplets are not part of the solution.

Alcohols, like rubbing alcohol are also polar molecules, but they are organic compounds, this means they have at least one carbon atom, the longer the carbon chain, the less likely the molecules are soluble in water.  The carbon chain helps the compound bring non-polar compounds into solution. So alcohols like isopropanol (which pretty much makes up rubbing alcohol) can act as a solvent for non-polar compounds like dyes and fats.

This is why you see both rubbing alcohol and hairspray recommended to remove ink from fabric. The alcohol brings the ink into solution where it can be wicked away with a paper towel or cloth.

Rubbing alcohol, can strip the fats and oils that protect your skin.

If this is allowed to happen for a long time, this can lead to cracking which can set you up for dermatitis and other even less fun infections.  Use gloves or limit the contact with your skin.

When used properly rubbing alcohol is a fairly safe cleaning agent. The main problem is its effectiveness as a solvent, sometimes it will destroy the item you’re trying to clean. You must use care and understand that alcohols are not always a safe choice for some surfaces and finishes.

Keep rubbing alcohol away from many painted surfaces, shellac, lacquer, and some man-made fabrics.

In some cases denatured alcohol -ethanol alcohol with bittering agents to make it unpalatable- may be a better choice. Don’t worry, I’ll get to denatured alcohol in a future article.

Send your questions to helpme@home-ec101.com

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Comments

  1. Marianne says:

    I really love when you explain how things work. Thanks for writing posts like this, Heather.

  2. Thanks for the info.I like to know how and why things work, but I failed hs chem.

  3. You might want to fix your isopropanol/isoproponal spelling confusion – all the alcohols have the -ol ending.

    Note that isopropanol does not burn all that hot. If you're going to set some flammable liquid on fire (after, say, soaking a tennis ball in it) isopropanol will get you something that's not nearly as scary as an ethanol or methanol flame, especially since the usual isopropanol solutions do have a fair bit of water. (I'm not saying you should do these dumb things, but if you're going to do them, you can take more liberties with isopropanol.)

    If a hot steady flame is what you're after (to run a model engine off of, for example) ethanol and methanol are good choices.

    • Thanks, I read it over 3 times and still missed it. I know it ends in ol, my fingers just enjoy al for some reason. I also cannot type weird or familiar correctly the first time.

      They do have their uses, but flames when they aren't expected, even low temperature ones aren't a good thing.

      Chemistry can be a lot of fun in a controlled environment. Accidental? Not so much.