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Speaker 1: Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,

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Speaker 1: I'm Christian Sager and not to get too personal, but

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Speaker 1: when did you last wash your jeans? You don't have

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Speaker 1: to tell me if you don't want to. But here's

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Speaker 1: the thing. Whether you're wearing a pair of busted Levies

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Speaker 1: or brand new raw Denham from some fancy boutique, your

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Speaker 1: pants are part of a debate that designers and customers

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Speaker 1: alike have been having for decades. When should you wash

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Speaker 1: your jeans? And do you need to wash them at all? Well,

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Speaker 1: let's look at the basics. Denim is a kind of

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Speaker 1: cotton with a twill textile weave. In a twill weave,

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Speaker 1: the thread called the weft that's the cross wise yarn,

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Speaker 1: passes under at least two warp threads, and those are

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Speaker 1: the lengthwise yarns. In most genes, only these warp threads

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Speaker 1: are dyed, meaning that these other threads, the weft threads,

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Speaker 1: remain white. That's why blue jeans are white on the inside.

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Speaker 1: That blue shade on the warp thread comes from a

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Speaker 1: dye called indigo, and unlike some other dyes, indigo doesn't

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Speaker 1: penetrate the cotton. Instead, it sits atop the yarn on

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Speaker 1: the surface of each thread. Over time, molecules of indigo

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Speaker 1: chip away, causing the fabric to fade. This fade makes

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Speaker 1: each pair unique, so much so that the FBI analyzes

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Speaker 1: Denham patterns when tracking criminals. Yeah, that's a real thing.

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Speaker 1: The more you wear a pair, the more broken in

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Speaker 1: they've become. You'll see the appearance of fade patterns, whiskers

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Speaker 1: on the front, honeycomb patterns behind the knees, and so on.

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Speaker 1: Not all genes, however, were created equally. Let's divide them

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Speaker 1: into two rough categories. There's washed and raw. Washed Denham

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Speaker 1: is just that washed after dying to make the fabric

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Speaker 1: softer and reduce shrinkage. Then, in a process called sanforization,

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Speaker 1: the trousers are moistened, steamed, and stretched to reduce the

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Speaker 1: shrinkage rate. Most genes are sanforrized these days. Raw or

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Speaker 1: dry Denham can be samporized or unsaforrized. If it isn't,

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Speaker 1: it can shrink up to ten percent when washed. Sometimes,

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Speaker 1: washed Denham is artificially distressed to give it a broken

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Speaker 1: in or worn look. The fading of raw Denham, on

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Speaker 1: the other hand, happens naturally over time, depending on the

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Speaker 1: daily activities of the person wearing the jeans. The longer

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Speaker 1: you go without washing these genes, the more pronounced fading

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Speaker 1: patterns will become. Personalizing your pants. Once you have a

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Speaker 1: pair of jeans, you'll hear numerous pieces of advice about

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Speaker 1: caring for them. Most of this doesn't apply across the board.

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Speaker 1: For example, companies will ask you to wait at least

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Speaker 1: six months before washing your jeans because if you wash

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Speaker 1: them early, the indigo will wear off uniformly, robbing you

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Speaker 1: of the unique fade patterns. And this is the heart

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Speaker 1: of the whole to wash or not to wash question.

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Speaker 1: The longer you go without washing a pair of jeans,

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Speaker 1: the more pronounced the wearing pattern becomes. You'll also preserve

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Speaker 1: the indigo as well as the stiff texture of the fiber.

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Speaker 1: But what happens if you don't wash them. Won't bacteria

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Speaker 1: pile up, turning your lower hemisphere into a plague written

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Speaker 1: cesspool of filth? Well not necessarily in A microbiology student

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Speaker 1: at the University of Alberta went get this fifteen months

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Speaker 1: without washing his genes. He tested their bacterial content along

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Speaker 1: with the bacterial content of another pair that had been

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Speaker 1: washed about two weeks beforehand, and he found almost no difference.

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Speaker 1: So maybe it's more that everything we wear is already dirty.

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Speaker 1: So if you can't wash them, what do you do

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Speaker 1: to keep your blue jeans clean? Well, you're gonna hear

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Speaker 1: some crazy stuff. Levi's famously recommended freezing your genes to

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Speaker 1: kill bacteria and stave off any funky odors, but microbe

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Speaker 1: expert Stephen Craig Carry says that is a total myth.

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Speaker 1: Most bacteria in our pants comes from our skin, and

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Speaker 1: a lot of these organ is ms are preadapted to

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Speaker 1: low temperatures. Carry recommends actually using high temperatures think a

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Speaker 1: hundred and twenty one degrees celsius for ten minutes to

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Speaker 1: get rid of the denom or bacteria or you know.

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Speaker 1: He adds, you could just wash them. So depending on

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Speaker 1: how often you wear your jeans, their age, the denom type,

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Speaker 1: and what you do while you're wearing them, you really

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Speaker 1: don't have to wash them as often as say you're underwear.

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Speaker 1: If you want to get that uber cool, unique fading pattern, though,

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Speaker 1: your best bet really is to avoid washing them for

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Speaker 1: a while, even if you have to soak them first

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Speaker 1: to shrink them, and regardless of how carefully you care

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Speaker 1: for your favorite pair of raw Denom jeans, messes like

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Speaker 1: life find a way. One day, some sort of disaster

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Speaker 1: will strike and you'll have to clean your genes somehow, Yes,

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Speaker 1: even if that means washing them. Check out the brain

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Speaker 1: suff channel on YouTube, and for more on this and

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Speaker 1: thousands of other topics, visit how staff works dot com

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