Women's underwear built in liner

March 22, 2016 6:06 PM

My 6 year old asked me a question that I honestly don't know the answer to. Maybe Metafilter does. Why do women's and girl's underwear only have the built-in shield/liner sewn in on three sides? And why isn't it sewn down in the front? Is this for faster manufacturing or something I haven't considered?
posted by wildeepdotorg to Clothing, Beauty, & Fashion (22 answers total)

Best answer: I think it's that it's often made of a different blend of material, and so the underpants themselves might have more stretch in them than the liner does. By sewing it on not all sides, it doesn't matter that it doesn't stretch as much and it won't tear.
posted by lollusc at 6:11 PM on March 22, 2016 [3 favorites]

That isn't universally true -- many of my pairs of underwear are sewn down on all four sides. I think it depends on the construction of underwear. If the crotch piece is separate from the main front and back pieces, it can easily be sewn down and inverted to get the seams to the inside, but if they're trying to create underwear with fewer seams, so that the crotch is connected to the front or back or both, then it can't.
posted by jacquilynne at 6:22 PM on March 22, 2016 [4 favorites]

Previously.
posted by mostly vowels at 6:26 PM on March 22, 2016 [3 favorites]

To build on what jacquilynne said, I have always worn underwear that has been sewn on all 4 sides, and only recently purchased some pairs that are only sewn on three. I remember wondering what the pocket was for: to hide something really, really well? So that you would never be able to access it politely?

Now you're telling me that most underwear are only sewn on three sides. What is life?
posted by chainsofreedom at 6:27 PM on March 22, 2016 [5 favorites]

One of life's greatest mysteries. I always assumed it was a result of cost saving calculations. Thread to sew liner on all sides of one pair of underwear: fractions of a penny. Thread to sew liner on all sides of one hundred thousand pairs of underwear: fifty cents.

Also, why do we call them "pair" of underwear?
posted by teamnap at 6:36 PM on March 22, 2016 [7 favorites]

Mine are only sewn on 2 sides, i just checked.

The long sides, if you must know.
posted by lizbunny at 6:47 PM on March 22, 2016 [8 favorites]

> Also, why do we call them "pair" of underwear?

Because pantaloons were two separate legs.
posted by clerestory at 6:52 PM on March 22, 2016 [7 favorites]

Ok, or apparently just English. Some places you find the separate legs thing.
posted by clerestory at 6:55 PM on March 22, 2016 [1 favorite]

Many of my childhood bathing suit bottoms also had this "feature". That's why I still think it's a special pocket designed to accumulate an obnoxious bolus of beach sand - to weigh down your bathing suit, and destroy your coastal holiday happiness.
posted by Coatlicue at 7:00 PM on March 22, 2016 [46 favorites]

I'm gonna go with the theory that the lining and the panty fabric are going to wear and shrink at different rates. Having a loose side allows that to happen without producing pucker.

If that's not it, it's the savings - not 3" of thread, but the extra sweatshop time it would take to sew them all down, when 3 will do.
posted by Miko at 7:01 PM on March 22, 2016 [1 favorite]

This question has also been asked on reddit, Yahoo, Quora, MedHelp, and Straight Dope forum.
posted by Miko at 7:02 PM on March 22, 2016 [1 favorite]

My standing theory: It reduces lumpy seams in the part of your underwear where you don't want lumpy seams. Picture how the back of the liner is stitched down, that back seam contains five layers of fabric compared to the two at the front. On the few pairs that I have where the front is stitched down, it's just the raw edge overlocked down with no folded up seams that add additional bulk, which probably also makes assembly easier.
posted by yeahlikethat at 7:04 PM on March 22, 2016

Coatlicue, it's worse with a swimsuit with a four-sides-sewn crotch. The fine sand gets in and it can NEVER BE REMOVED. The horror.

I assumed it's variation in fabrics because 100% cotton ones are usually sewn on all sides.
posted by 26.2 at 7:15 PM on March 22, 2016 [4 favorites]

I have never seen a pair of underpants with only three seams on the liner in my entire life. I just checked my underwear drawer to make sure. Is this something you only get with expensive clothes? I don't buy anything fancier than Hanes.
posted by The Underpants Monster at 8:21 PM on March 22, 2016

Best answer: It's cheaper to manufacture, it's easier to work with different fabrics with different tolerances, fewer seams under your bottom.
posted by oneirodynia at 8:51 PM on March 22, 2016

Yeah I put it down to basic cotton-y undies saving money and fabric. If you want to sew that front part you either need to have another seam or fold under some of the edge slightly to tack/serge it down. Just barely surging (stitching over) the front edge saves fabric, thread, and money. Not to mention it's an extra step in the process which they want to make as quick and seamless as possible (couldn't help myself.) Another seam is another step, more labor, and possibly more machinery.

That said, most of my "fancier" (cuter designed) undies tend to have it all tacked down. Though generally that's because they're actually two layers of fabric inside and out. Like a lacy layer and an inner layer with a smoother cotton in the crotch. I just check what I'm wearing and it's two layers of fabric with a fully seamed crotch.

So I think the basic panty design comes down to manufacturing convenience, but it depends on the brand and style.
posted by Crystalinne at 10:44 PM on March 22, 2016

Best answer: Oh and not to mention if the fabrics stretch at different rates, so if the liner is cotton and the outer shell is something else. Trying to wrangle fabric that each has a different ability to stretch is a nightmare.
posted by Crystalinne at 10:45 PM on March 22, 2016 [1 favorite]

I'm 49 and have owned a LOT of underwear over the decades, but I've never seen what you are describing. I'm befuddled. If I got something like this, I'd assume I got a "dud" just as if one of the side seams were ripped.

We're talking about the gusset, right? And you're saying all sides of it are not stitched down? I've owned the three-(or five)-to-a-pack cheap kind and the fancy-schmancy "OMG, I can't believe I spent that on underwear" kind, nylon or satin with lace, microfiber and seamless, plain cotton -- but no unsewn anything. Every once in a while, a friend jokes she's going to replace MeFi with a hoax page only I see, but Googling shows multiple people on the web have asked this question. I've no problem accepting the "cheap manufacturing for maximum give" explanation; I'm just weirded out by the existence of something I've bought many hundreds of having a completely different variation. What else do you all have that I don't, and vice versa?
posted by The Wrong Kind of Cheese at 12:23 AM on March 23, 2016 [1 favorite]

Response by poster: @Miko, not the same question. I know why the cotton is there -- just not why it's sewn the way it is.

@The Wrong Kind of Cheese and @The Underpants Monster -- I've worn everything from Victoria's Secret to department store underwear to tagless Hanes (nylon and 100% cotton among all of them) over the years and never seen the crotch sewn on all four sides. My daughter wears Hanes and whatever brand makes Paw Patrol underwear.

Clearly it's the uniqueness of the human experience!
posted by wildeepdotorg at 4:07 AM on March 23, 2016

I've worn everything from Victoria's Secret to department store underwear to tagless Hanes (nylon and 100% cotton among all of them) over the years and never seen the crotch sewn on all four sides. My daughter wears Hanes and whatever brand makes Paw Patrol underwear.

This is so weird. I just went and checked all the underwear in our house. Everything (including tagless cotton Hanes & girls' cotton Paw Patrol underwear) has all 4 sides sewn down. I can only remember one pair I've owned that had an open side, and that was a "fancier" nylon pair. I wonder if it's a regional difference?
posted by belladonna at 5:23 AM on March 23, 2016

@Miko, not the same question.

It comes up in the comments; I thought it was sort of implied in the "pocket" discussion. Anyway, the Quora answer is particularly good.
posted by Miko at 7:36 AM on March 23, 2016 [1 favorite]

I think it depends on the fabric and it's due to shrinking and seams. Not really a big deal.
posted by Georgia Is All Out Of Smokes at 2:53 AM on March 24, 2016