BrainStuff Classics: Do You Really Need to Wash Your Jeans?

don't want to. But here's the thing. Whether you're wearing a pair of busted Levies or brand new raw Denham from some fancy boutique, your pants are part of a debate that designers and customers alike have been having for decades. When should you wash your jeans? And do you need to wash them at all? Well, let's look at the basics. Denham is a kind of cotton with a twill textile weave. In a twill weave, the thread called the weft that's the cross wise yarn, passes under at least two warp threads,

and those are the lengthwise yarns. In most genes, only these warp threads are dyed, meaning that these other threads the weft threads remain white. That's why blue jeans are white on the inside. That blue shade on the warp thread comes from a dye called indigo, and unlike some other dyes, indigo doesn't penetrate the cotton. Instead, it sits atop the yarn on the surface of each thread. Over time, molecules of indigo chip away, causing the fabric to fade.

This fade makes each pair unique, so much so that the FBI analyzes denom patterns when tracking criminals. Yeah, that's a real thing. The more you wear a pair, the more broken in they've become. You'll see the appearance of fade patterns, whiskers on the front, honeycomb patterns behind the knees, and so on. Not all genes, however, were created equally. Let's divide them into two rough categories. Is washed and raw. Washed Denham is just that washed after dying to make

the fabric softer and reduced shrinkage. Then, in a process called sandforrization, the trousers are moistened, steamed, and stretched to reduce the shrinkage rate. Most genes are sanforized these days. Raw or dry denham can be saporized or unsanforrized. If it isn't, it can shrink up to ten percent when washed. Sometimes, washed denham is artificially distressed to give it a broken in or worn look. The fading of raw denham, on the other hand, happens naturally over time, depending on the

daily activities of the person wearing the jeans. The longer you go without washing these genes, the more pronounced fading patterns will become. Personalizing your pants. Once you have a pair of jeans, you'll hear numerous pieces of advice about caring for them. Most of this doesn't apply across the board. For example, companies will ask you to wait at least six months before washing your jeans because if you wash them early, the indigo will wear off uniformly, robbing you

of the unique fade patterns. And this is the heart of the whole to wash or not to wash question. The longer you go without washing a pair of jeans, the more pronounced the wearing pattern becomes. You'll also preserve the indigo as well as the stiff texture of the fiber. But what happens if you don't wash them. Won't bacteria pile up, turning your lower hemisphere into a plague written

cesspool of filth. Well, not necessarily in. A microbiology student at the University of Alberta went get this fifteen months without washing his jeans. He tested their bacterial content along with the bacterial content of another pair that had been washed about two weeks beforehand, and he found almost no difference. So maybe it's more that everything we wear is already dirty. So if you can't wash them, what do you do to keep your blue jeans clean? Well, you're gonna hear

some crazy stuff. Levi's famously recommended freezing your genes to kill bacteria and stave off any funky odors, but microbe expert Stephen Craig Carry says that is a total myth. Most bacteria in our pants comes from our skin, and a lot of these organisms are preadapted to low temperatures. Carry recommends actually using high temperatures think a hundred and twenty one degrees celsius for ten minutes to get rid of the denom or bacteria or you know. He adds,

you could just wash them. So depending on how often you wear your jeans, their age, the denom type, and what you do while you're wearing them. You really don't have to wash them as often as say you're underwear. If you want to get that uber cool, unique fading pattern, though, your best bet really is to avoid washing them for a while, even if you have to soak them first

to shrink them. And regardless of how carefully you care for your favorite pair of raw Denom jeans, messes like life find a way one day, some sort of disaster will strike and you'll have to clean your jeans somehow, yes, even if that means washing them. Today's episode was written by Ben Bollin and produced by Tyler Clang. For more on this and lots of other topics, visit our home planet, how stuff Works dot com