
The Physics of Bras - chaostheory
http://discovermagazine.com/2005/nov/physics-of-bras
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kingsley_20
What follows are the musings of an ex-lingerie designer.

Side note: Humans, btw, are the only animals that sport full breasts all
through their youth. Most mammals, including all simians and apes, only sport
enlarged breasts when feeding their young.

Simplistically, cup-size is the chest-to-breast ratio, designed to compensate
for the fact that radius of the cup is almost, but not entirely, independent
of the chest circumference. It does not have a strong correlation to volume of
the cup or to mass, although acute cup-sizes are more common at larger chest
sizes.

Human bodies grow very disproportionately at either extreme of size. For
example, height is a very poor indicator of girth, although it bears a small
correlation, and vice versa. Similarly, larger women have a higher incidence
of acute cup-sizes, but the shape, consistency and mass of the breasts are
very different from what you'd expect through linear scaling.

Ultimately, larger women are a different market. It's common for a larger
woman to have large breasts that have a small footprint on her torso. Most
lingerie does not account for this. Most lingerie is also not built to bear
the weight/consistency of larger breasts. You need to use load-distributing
design, as well as resilient/soft materials to ease the stress on the back.
And then, you have to put the whole thing together into a sexy package. It
almost make it more fun to write code :)

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Mz
Wondering if this upvoted article will generate any serious discussion. I
stopped counting after I had gone through 9 different bra sizes over the
years. I found the article quite interesting.

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ciupicri
Do you have any idea what caused this? I have yet to met someone with such a
huge variation, except mothers who are breast feeding, but that's another
thing and it's expected.

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silencio
I'm not sure why that's a surprise, I'd be surprised if a woman _didn't_ have
a wide variation of sizes to choose from. Not only are "standard" bra sizes
not entirely the same across manufacturers, but also there are all sorts of
different types of bras out there to get different looks. And that's not even
considering how physically different breasts can get, even for a specific
woman depending on the day.

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physcab
I remember in one of my materials classes they used bras as an example where
martensitic metals were used. Apparently these materials were chosen to help
bras retain their shape (such alloys are also called shape-memory alloys).
However, shape memory alloys usually deform back once heated. I've always
wondered if this was true. Anyone who has ever washed theirs in hot water want
to confirm?

~~~
Mz
Generally speaking, it's a bad idea to toss bras in a washer and dryer on high
heat. Ideally, they should be hand-washed. If that's too much hassle, one
should at least put them in mesh lingerie bag so the straps don't get all
tangled up with parts of the washer and other clothes, which tends to deform
the straps. The hooks of a bra can also get caught on other clothing and
damage the other clothing. Washing bras in hot water generally shortens their
lifespan. A good bra can be quite pricey so some women who hand-wash nothing
else do hand-wash their bras, especially if they are hard to fit.

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tianaco
There is definitely an under-served niche here. From my conversations with
other busty women, most bras and swimwear are either un-fashionable or ill-
fitting, or un-supportive.

I recently decided I would learn to sew my own swimwear and bras since most of
what fits me is horribly ugly and overpriced... I'm in my 20's,
fit/5'8"/narrow ribcage/large cups. Forget about factoring support into the
equation.

After 10 years of spending hours and hours every spring/summer looking for the
perfect fitting bikini, I realized that in that same amount of time, I could
learn how to make my own swimwear and be set for the rest of my life. "give a
man fish he's fed for a day, teach him to fish he's fed for life"

Going through bra and swimwear patterns, I've learned that the construction
ranges from simple to very complicated. Unfortunately, nobody in the industry
appears to be doing anything that's particularly interesting or ground-
breaking. Very little that appears to be designed by and for a large-busted
woman. Patterns are classic, even corsetry-inspired. No new construction
methods or materials. Too bad because there is a huge market for supportive
and attractive bras - "of the future"?

Lululemon has some great sports bras that are very supportive and cute and the
price is reasonable. I wish more companies would follow suit.

What I'd really love is supportive bras with moisture-wicking materials
covering the underwire. I have no idea why no companies that I know of, other
than Lululemon, have capitalized on this. It's so obvious to me!

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dustingetz
holy mother of "A pair of D-cup breasts weighs between 15 and 23 pounds—the
equivalent of carrying around two small turkeys."

~~~
DarkShikari
That statistic seems slightly off to me.

If we assume that the breasts are the same density as water (which is probably
too high, as they're mostly fat, which is less dense than water), 23 pounds is
about equal to a 12 inch by 7.5 inch by 7.5 inch block of pure flesh.

Maybe it's just me, but I think that fails a simple sanity test.

Edit: Wikipedia says "The average breast weighs about 0.5 kilograms (1.1 lb)"
with some decent sources, and given that the average bust is a C-cup, I highly
doubt that a D-cup weighs 5-10 times more than that.

~~~
scott_s
"D-cup" also isn't enough information to gauge volume. A 36-D is larger than a
34-D. And remember that volume (and hence mass) increases as the cube of
length, so two inches more in length will mean a lot more mass.

~~~
DarkShikari
Of course. I assumed that "15-23" would mean "average", so since the average
band size is around a 36, that would probably mean "32D-40D" or something of
the sort for "15-23".

Either way, the numbers seem absurd.

~~~
brisance
Volume of cone = pi * r^2 * h / 3.

Plugging in r1 of 3 and r2 of 2.5, and h1 of 36 and h2 of 34. Constants cancel
out, that's an increase of 2.38 times in volume.

This is per cone ;)

~~~
arithmetic
Exactly the way I'd expect nerds to discuss breasts :)

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btilly
The article punts on why women have breasts. For interesting speculation on
that topic and several related ones, <http://davidbrin.com/neoteny1.htm> is an
interesting read.

~~~
Mz
Desmond Morris, who wrote "The Naked Ape" and some other books, said some very
interesting things about human anatomy and human sexuality.

<http://en.wikipedia.org/wiki/Desmond_Morris>

<http://www.desmond-morris.com/>

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rokhayakebe
I think starting a bra comparison site with reviews and comments would be
great.

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notauser
Wouldn't it be very subjective? Reviews of walking shoes are pretty useless,
for example.

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rokhayakebe
I don't know, but when I saw 5B annually my brain started to work very fast.

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mhb
The timeless classic _Why Women Have Breasts_ :

<http://www.lloydianaspects.co.uk/evolve/breasts.html>

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gaius
What does it say about me that I first read that as "The Physics of Brass" and
it was no less interesting?

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mapleoin
For the first part of the article I was still waiting for a connection between
breasts and brass.

