Skunks have a seriously stinky defense mechanism. Why does skunk spray smell so awful, and how do you fight it? The answer lies in chemistry!
My household was recently hit hard—nausea, vomiting, watery eyes. No, it wasn’t the flu. It was a skunk.
In a valiant effort to protect the backyard, our dog was sprayed right in the face. She then tore through the house like a tornado, trying to run away from the smell (and her own face) for 30 fateful seconds before we realized what was going on.
The smell was everywhere.
At first I hadn’t been able to place the incredibly strong smell, but it set off alarm bells in my brain. I remember thinking that perhaps something was burning.
If you’ve been unlucky enough to smell skunk spray up close, you know it smells very different from the odor you may catch a whiff of when you encounter roadkill or otherwise pass at a distance. At first, I hadn’t been able to place the incredibly strong smell, but it set off alarm bells in my brain. I remember thinking that perhaps something was burning. In the immediate aftermath, all of us vomited, including the dog. Our eyes watered and burned as if the air was thick with tear gas.
As defense mechanisms go, skunk spray is impressively effective. Skunks can reportedly aim their "weapon" accurately as far as 7-15 feet away. And it turns out that what makes skunk spray so powerful comes down to chemistry.
Why does skunk spray smell so bad?
The contents of a skunk’s spray depend on the species of skunk. In North America, there are six: the Eastern and Western spotted skunks, the hooded skunk, two species of hog-nosed skunk, and perhaps the most recognizable, the striped skunk. But despite their differences, all species employ a spray that contains smelly molecules called thiols. These are chains of carbon and hydrogen atoms with one sulfur atom and one hydrogen atom attached on one end.
What makes skunk spray so powerful comes down to chemistry.
Sulfur atoms are known for making things stink, like rotten eggs, burnt rubber, or raw onions. Thiols have the additional quality of being easily spread or dispersed in the air. So the initial punch of skunk spray is already pretty deadly.
Scientists studied skunk spray in the 90s to determine its specific components. The group, led by William Wood at Humboldt State University, needed a sample of an organic compound called trans-1-butene-1-thiol for some of their other work. The compound isn’t something you can just buy on the internet, so they decided to find out if they could extract it from skunk spray. They sedated four skunks and extracted the secretion from their anal glands. I can only imagine what their lab smelled like.
They were able to determine the components making up the spray using a very common analysis technique called mass spectrometry. Essentially when placed in a mass spectrometer, the components of a sample are separated by their atomic weights so that they can be identified. They are first converted to ions so that electromagnetic fields can direct their movements, and then sorted based on mass and charge. A mass spectrum is then produced, which shows the relative amounts of compounds of each mass and charge present. So, this means you can identify the components of a particular sample and even identify new compounds.
The researchers found three major thiols in the spray, two of which are responsible for the smell and account for ~50-70% of the secretion: (E)-2-butene-1-thiol and 3-methyl-1-butanethiol.
As if those weren’t bad enough, skunk spray also contains another type of compound called thioacetates, which aren’t initially smelly but become smelly once they interact with water. This group of carbon and hydrogen atoms undergo a chemical reaction with good old H2O to become more potent thiols. That means when you try to bathe or rinse off the skunk spray, it just gets worse.
How do you get rid of skunk odor?
One common myth is that you can use tomato juice to combat skunk smell, but that doesn’t work. You’ll just get one strong odor lightly masked by another. Unless you want you or your pet to smell like Eau de Skunk with a dash of Bloody Mary mix, you'll will need to get deeper into the chemistry and neutralize the thiol compounds doing the damage. In other words, you need to take away the ability of these compounds to stink. You can do this by adding oxygen atoms to the mix that bonds with the thiol and convert them into a sulfonic acid and disables its stench in the process.
One common myth is that you can use tomato juice to combat skunk smell, but that doesn’t work. You’ll just get one strong odor lightly masked by another.
Two common oxidizing agents are baking soda and hydrogen peroxide. The most commonly recommended recipe for skunk de-stencher is to combine 1 quart of dilute (3%) hydrogen peroxide with ¼ cup of baking soda, 1-2 teaspoons of liquid dish soap, and water if you need to dilute the mixture to cover a large surface area ... like one large dog.
In less than a minute, the smell of that skunk spray left a mark on our house that lingers months later. As a scientist, I immediately turned to the internet for published research on how to get the stench out of our home and our lives and found the chemistry-backed work of Wood and his colleagues that I just mentioned.
But I was also desperate to stop wondering whether my colleagues weren’t going to sit with me at lunch because I still smelled. That made me willing to try some, shall we say, less evidence-based methods rumored to fight the smell amongst popular internet lore.
I did not douse myself in tomato juice, but I placed bowls of vinegar, which allegedly absorbs the odor, in the rooms that were worst hit. I doused our couch in the specifically skunk-branded Nature’s Miracle recipe. I’m not sure the vinegar did much, but the Nature’s Miracle seems to have rescued our couch.
Anecdotally, I can say from experience that the baking soda and hydrogen peroxide recipe was most effective. You may have to apply it many, many times to see complete success, but it knocks out a big part of the initial stench.
The most important fix, however, might turn out to be time. Skunk smell can reportedly continue to stink up your skin and hair for a few weeks and live on in fabrics for up to a year. Luckily for most of us, skunk spray is easy enough to avoid. Skunks usually give warning signs before they spray. They hiss, stomp, and one species even does a handstand. And hopefully, my dog has learned an important lesson.