How certain bands may pull the underwires broader and make the cups fit badly. This information might be crucial to you if you wear bigger cups.
Important! I have re-written this post because the old one was quite inaccurate.
Recently a lovely reader shared her bra-fitting dilemma with me, where her band wouldn't lie flat on the sternum even though it was pretty snug. The photos showed that probably the band construction is at fault here. The band was a three-piece one, and it was not stable enough to stay on the ribcage and keep the cups in place. Instead, it allowed the breast to slightly slip below.
There are two kinds of bands: ones that go along the entire bra in almost one piece (a part of the band continues below the cups), and ones that are connected only to the sides of the cups (this band is made of three separate pieces). Now, when I looked at my Panache Porcelain, I realised that in a 3-piece band the center part can be either a proper piece of fabric (middle pic), or a narrow band (top pic).
This is what it looks like:
A "three-piece band" bra can be more or less stable depending on how big the middle piece is: if it is a narrow tape, try stretching the band and it's likely that the underwires will stretch too, making the cups broader and shallower. (Of course, this also depends on what material the underwires are made of, some are more bendy than others.) This kind of band doesn't hug the torso as tightly as a one-piece band, so it might try climbing on top of your boobs. Basically, no self-respecting bra brand will make bras with such a crappy construction.
If the middle piece of the band is as high as it is broad, it will actually hold the cups in place and will be almost as stable as a one-piece band.
A "continuous" band stays below the rib-cage and keeps the cups in place. The cups and underwires are more likely to not stretch when pulled. I'm guessing that these kind of bands take more skill and works to make, as compared to the cheapo three-piece band. You'll notice that most "real" bra brands make their bras with almost exclusively "continuous" bands.
This is what the two kinds of band look like in real life:
The bra on the top is Chili from Ewa Michalak with beautifully constructed three-piece cups. The middle one is the Panache Porcelain. The one at the bottom is from a brand that shall remain unnamed.
So the next time you are going lingerie shopping, take a look at what kind of bands the bras have. Obviously, this is more important for fuller-busted gals, who naturally need more support. Not all bras with three-piece bands are bad, especially if they are from bands with firm underwires and generally supportive bras.
Have you ladies had issues with three-piece bands that are connected with a piece of tape, or do you find them ok for your breast type? What else do you watch out for when checking the band construction?