Around the globe or "what the nice saleslady won't tell you"

Hi everyone. Today, I'd like to discuss breasts.
Dear male readers, my apologies but this post is really for those who have breasts, wear bras and may considers making those. Regular posting about sewing, clothes and the like will resume with the next post.

In her comment to my previous post, The Perfect Nose (about whose own explorations into bra pattern making I told you in that post) asked if it's wouldn't be worth it to make a bust form to test my bra patterns. I have to admit it sound like a great idea but I happen to know it is not as easy as it sounds.
When I made Mary, my ductape body double, I had trouble with her curves straight away. Once I had been cut out of it, all the stick-out bits just lost their real size shape very easily. The breast were an even bigger issue. I don't remember whether or not I was wearing a bra when I was being wrapped in tape to create Mary. I think I wasn't. I should have worn one though. A fitted t-shirt (the appropriate underlayer for a ductape dummy) will make the breasts a bit flatter anyway. Add some tightly wrapped layers of tape and there will be preciously little curve left. 
As a result, the top I draped on Mary was always a bit snug around the chest...

Of course, I have learned from the Mary experience but nevertheless, I'm sure I wouldn't be able to create a bust form which would actually work for the purpose of helping me draft bra patterns. Not even with professional dummy maker help.
The pattern maker's study of breast has something in common with sub-atomic partical physics: it's just not possible to measure the damn things without influencing them. And if you could accurately measure one property, you'd still be completely in the dark about other important properties. 
In the case of breasts, one might succeed in making a bust form which shows the breast in its proper size and shape, but real breast are soft tissue...

As a start, what is a breast's "proper shape" anyway? It's natural, unsupported shape? The natural shape it had when it first reached its full size? The shape it has when supported by a favorite bra?
Vintage fashion lovers will be well aware of the changing ideas about this over time: from the pigeon chested monoboob of the Edwardian era to the flat-chested "garconne" of the 1920's and from the conical shapes of the 1950's to the natural look of the 1970's... And if you think we're all about "supporting our natural assets" today, take a good look at the contents of any lingerie store: Most are filled back to front and top to bottom with foam globes. Don't get me wrong, I'm not against foam cups per se, but I think it's not correct to think of that as a natural shape. And don't get me started on those push-ups which are ever increasing in size (personally, I am against those)

Just stand in front of a mirror without a bra on: breasts tend to be more or less drop shaped, round at the bottom and hanging in a straight line from the upper rib cage at the top, and pointy towards the nipple. 
In my work, I've fitted a lot women for bridal lingerie. In the process, I've learned about all those fitting issues which are not captured in bra sizes. 
Women's breasts vary in size, shape and in what I would here, for the sake of the discussion, like to call "texture": the degree of softness or firmness of the tissue. All these vary over the course of one's life depending on influences such as age, weight fluctuations, pregnancy and nursing, exercise and the degree of support the breasts received during those changes. 

Typically, bra sizing is based on the difference between bust measurement (measured at the fullest point, often when wearing a bra. this is because larger or softer breasts will hang significantly lower when unsupported) and underbust measurement. However, the same measurements won't even put you in the same size of different brands. Some use stronger or less strong elastic for the band, which influences the circumference size needed for each wearer. Similarly, each brand's definition of cup size may be different. 
I suppose I don't have to tell you (although I've come across a lot of women who don't know this) how bra sizing works: cup sizes are defined in relation to band sizes. As a result the size of the underwire itself for a 70E is the same as that for a 75D, 80C, 85B and 90A. The size of the underwire and the content of the cup. So, in fact, a statement like "I always wear a B cup" is meaningless....
The letters don't mean anything on their own. The sizes I mentioned are the ones we use in the Netherlands: band sizes in centimeters. In other countries, other systems are used but there is always this relationship between circumference and cup size.

At a fitting, your size will be determined based on the difference between those two measurements. However, that opens up a minefield of issues. For example, sporty ladies may be put into too large a cup size because strong, and therefore a bit bulky, back muscles are measured into that all-important bust measurement. Much more common, especially in smaller sizes, is another issue: there is now fixed relationship between breast surface on the ribcabe and breast volume. Most bra brands shape their cups in the same way for all sizes (maybe with some extra support for for larger sizes), just making them larger or smaller on a linear scale. Women with breasts tend to have a flat chest, rather than small round breasts with more space around them. In a lot of cases  , women with A cup measurements (for any circumference) have breasts with a surface on the ribcage which is wider than an A cup underwire. 
Underwires have to fit around each breast. If they don't, the bra will, in effect, push the breast tissue that sits under and outside the wire towards the armpit and, over time, damage the shape of the breast. 
As a seamstress making a bra, you have the option of going with the wire size you need and adapting the volume of the cup. If you know you may need to do this, pick a pattern with a seam which runs over the middle of the breast. Make a muslin, with a the underwires in place, try it on and pin out excess fabric along that seam. 

So far, we've actually only discussed general sizing, the problems with that and one issue when fitting breasts singly. Most of us (and all of us who shop in regular lingerie stores and/or buy commercial bra sewing patterns) have two breasts. Fitting both of them well presents even more problems. These issues are more often felt by those with larger sizes. It has to do with breast placement on the ribcage. In each bra, the breast is assumed to be in a certain place. Of course, all commercial brands have fitting models and good ones may have large files about women's shapes and sizes, so that placement will largely be in line with that of the breasts of the average woman. But who is to say you are average? 
Add to that the fact that no brand ever fits for all sizes separately, and you will begin to see the problem. By the way, this is also why, above a D cup, bras from from brands which specialize in larger cup sizes will often fit better. "Normal" brands assume 75 or 80B is the standard size (although now, many have moved on to 75 or 80C), fit their designs for that size and grade up and down from there. Specialist brands will fit their designs on a fit models who have a size which is average in their size range.
No matter what size you have, you should always pay attention to how the underwires sit on your body. They should lie flat on the ribcage around your breasts. If they are pushed forward in the middle, the bridge of that particular bra is too wide for you. I don't have a large cup size and I had to adjust my self-drafted pattern a little bit for this. At work, I see this issue often in the D+ sizes (probably because corselette brands use a B or C cup as a standard). When buying bras, women with small cup sizes rarely come across this problem because most of the styles available to them are half-cup bras. This means the cups are partially cut away at the center front, eliminating a significant part of that potentially troubling bridge. Because larger breasts need more support, a lot of styles for larger cup sizes will have a full height bridge.

Wow, this is already a very information-heavy post. It's probably enough for now. I have a lot more to say about breasts and bras but I think I'll leave that for some other time.
Please let me know if you're interested in that sort of thing.