November 7, 2011
The Myth of the Frozen Jeans
Do you freeze your jeans? (courtesy of flickr user fogindex)
Levi Strauss advises freezing your jeans to kill the germs that make them smelly, thereby saving the water you’d use in washing them.
Don’t bother, says Stephen Craig Cary, a University of Delaware expert on frozen microbes, who wrote to us from Antarctica.
Most of the bacteria on your jeans probably started off on your own body. Since these critters are happiest living at the temperature of human skin, “one might think that if the temperature drops well below the human body temperature they will not survive,” Cary writes, “but actually many will. Many are preadapted to survive low temperatures.” And it takes only one survivor to repopulate your jeans when they warm up.
“I would suggest that you either raise the temperature to 121 degrees Celsius [250 degrees Fahrenheit, the temperature used for sterilization] for at least 10 minutes,” Cary writes, “or just wash them! The latter surely is the best alternative to save energy.”
Julie Segre of the National Human Genome Research Institute, who studies the skin’s microbiome, seconds the washing recommendation. “The bacteria that would live on your jeans [are likely feeding] on the sloughed skin and the dirt nutrients [on the jeans rather] than the jeans themselves, so detaching the sloughed skin could reduce the microbial load of your jeans,” she says. In her opinion, removing the dirt and the sloughed skin is more important than removing any bacteria, though she warns that she may have “just transitioned from speaking as a scientist to speaking as a mother.”
How often you wash your jeans may depend on how comfortable you are with the growing amount of dirt and sloughed skin on the fabric; the bacterial load doesn’t seem to be much affected by how often you go between washings. A somewhat unscientific experiment by a Canadian student found little difference in the bacterial load between one pair of jeans worn for 15 months without washing and another pair worn for 13 days.
So, sorry Levi’s, freezing our jeans sounded like a great idea, but it’s probably not doing anything more than taking up space better left for ice cream.
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most bacteria are not killed by any amount of cold. Most just go dormant or form spores. Heat kills as does a good washing–soap dessicates bacteria. Read a basic bacteriology text.
Comment by Richard — November 8, 2011 @ 8:27 am
It’s fine to talk in theory, but freezing does work to keep the jeans from smelling gamey. Rather than ask people who are experts on frozen microbes, it might be better to ask people who are experts on frozen jeans.
Comment by but did they try it? — November 8, 2011 @ 11:16 am
@ but did they try it? -
You’re using this word “theory.” I do not think it means what you think it means.
Comment by Sam — November 8, 2011 @ 12:17 pm
Interesting read and curious to learn more. How could one explain funky smells being eliminated after a freezer clean? Also, how is the Josh’s (the Canadian student) denim experiment unscientific? They took before and after samples and he only washed via freezer cleaning.
Cheers,
Rawr Denim
http://www.rawrdenim.com
Comment by Rawr Denim — November 8, 2011 @ 1:36 pm
Not sure I understand Stephen Craig Cary’s comment. Even if the jeans are washed, they’ll still be repopulated by being in such close proximity to the wearer’s skin.
This isn’t just about saving water either, it’s also about preserving the color.
Comment by Scott — November 8, 2011 @ 2:26 pm
I freeze my jeans. It works. I don’t stink, and my jeans aren’t fading NEARLY as fast, and they retain their shape way better this way.
I DO wash them, just not after every time I wear them.
Comment by I do it — November 8, 2011 @ 3:01 pm
@Richard: Many bacteria are in fact killed by very cold temperatures: the formation of intracellular ice crystals can cause cytolysis. So I don’t know about “most” bacteria surviving “any amount of cold”… but certainly *many* can. I’m being pedantic, perhaps.
@but did they try it: Bravo! That’s actually a more scientific approach than trying to arrive at the answer through reasoning alone. Using observations and not just trusting our logic is the fundamental reason science works – however, it also needs good experimental design. In this case, people’s perception that the jeans are less funky out of the freezer may be flawed (we are easy to fool), for example if we give them a test whiff straight out of the freezer when they’re cold, they won’t give off as much odour and we’ll think it worked. But then they warm up…
Haven’t read the experiment mentioned in the article.
Comment by Michael Strack — November 8, 2011 @ 4:02 pm
FWIW, as others have mentioned the suggestion of freezing jeans isn’t meant for energy savings.
It’s done by denim enthusiasts to avoid the change in color and creases that washing can precipitate, since the major reason to get raw denim is to create custom fading and creasing conforming to your body.
Comment by RandomInfo — November 9, 2011 @ 11:40 am
Levis is making a big deal about using less water to make their jeans. They try to make it an environmental thing, but the reality is they just moved their production to countries that don’t have a cheap supply of clean water for them to use.
Microbes eating dead skin, causing smells. Yeah, its time to wash your jeans.
Comment by Stephen — November 15, 2011 @ 11:14 am
My step sister used to dry clean her expensive jeans to keep them nicer longer, but freezing them is ridiculous. I have a hard time believing that Levis ever actually recommeded this. Science is science and freezing them could never clean them. That said, your best bet is to turn them inside out before washing them and most jeans don’t need a wash after each and every wear. I also think a little bit of starch keeps them fresher longer and prolongs their life as well.
Comment by JeansHub — November 16, 2011 @ 6:08 pm
I’m a 29 year old active man who enjoys upscale denim jeans. I’ve got a pair that I’ve worn regularly for almost 2 years and they’ve never seen soap.
Every few weeks, my jeans start to take on my bodily aroma. So, I bag ‘em up… throw ‘em in the freezer for 3 days… pull them out and bada bing, there’s no more smell. Science or not, it works. Give it a try before scoffing at the idea.
Idiots.
Comment by DenimFreezer — November 18, 2011 @ 8:23 pm
When you are talking about freezing jeans, you are going into the land of raw denim. That is when you talk to experts on jeans, people who buy raw denim, people who wear and are experienced with raw denim.
Getting to the nitty gritty and going to a expert on frozen microbes is not going to help. Yes, it will perhaps, if you are conducting an experiment.
However, if you are wearing raw denim and trying to clean them without destroying your jeans and running the dye. Then yes, freezing work. Even if it doesn’t kill bacteria, it does kill the smells that you may get from wearing them for months straight without a wash.
Comment by Vince W. — January 13, 2012 @ 2:12 am
Ok, I’m not in any way a denim enthusiast, actually got here by accidentally clicking on the wrong link. Either way, some people aren’t understand what the word CLEAN means. As many have said freezing the jeans makes the smell go away, but that does nothing to kill the bacteria that will eventually cause they smell again. Washing them kills the bacteria. “clean” and “not smelling bad” are two COMPLETELY different things.
Comment by some guy — March 11, 2012 @ 1:59 pm
The germ residue is still there. The dirt and dead skin is still there.
I would think its freeze drying the oils and moisture off the jeans thus making them less smelly.
So how much energy is the freezer using to do this?
Sounds like a hippie gimick.
Ha ha, “smelly hippie”!
Just don’t bath. That will save water.
I knew this guy who had a favorite sweater who gently washed it in distilled water no soap and dried it on a plastic window screen.
Thought he was using almost no energy this way until I pointed out that the distilled water was made by boiling and the amount of energy used to do this.
Comment by joe — April 16, 2012 @ 10:33 pm