It took me a long time to understand the difference between a partial and a full band bra. What’s so difficult to understand? A full band bra is a bra in which the cups are set into a frame, giving support to the breasts while also separating them, and a partial band bra is a bra in which there is no frame under the cups and the band and bridge are separate pieces, right? While that is true, it is only the tip of the iceberg. There is one major difference in the patterning of partial and full band bras that I blame for a fit issue I just recently solved – a year after I started sewing undergarments. Hopefully, by sharing what I discovered, which only made sense after I read, reread, and read many times over Beverly and Norma’s books, I can help others who have the same problem.
Like I wrote above. Bras fall into two categories – ones with frames, which are called full band bras, and ones without, which are called partial band bras. For both styles, the wire line sits at the base of the breast, indicated by the orange line in the image above, but the position of the seam that joins the cup to the band is different depending on the bra style. To understand this, let’s walk through the construction process of each kind of bra. On a partial band bra, the cup seam allowances, which are almost always ¼”, are stitched to channelling, which is also almost always ¼”. After the channeling as been attached, the seam allowance is flipped to the INSIDE of the cup and stitched a second time. So, on a pattern for a partial band bra, there is ½” between the cutting edge of the pattern and the wire line – ¼” for the channeling plus ¼” for flipping up the seam allowances. On a full band bra, the seam allowances, which are the same width as in a partial band, are also stitched to ¼” wide channeling. After the channeling has been sewn, the seam allowances are then flipped OUTSIDE and stitched a second time. So, on a pattern for a full band bra, there is ¼” between the cutting edge of the pattern and the wire line (because it doesn’t have to be flipped up). Here’s another way of saying it – the difference between the cups of a full band and a partial band is ¼” along the wire line or a partial band has an extra ¼” built into the pattern to account for the channeling being flipped to the inside of the cup. If you’re having a hard time visualizing this concept, the sketch above depicts it. See how on a partial band bra, the dotted line, which indicates the wire line, is father away from the pattern edge? This is why you can’t decide mid-sewing to change a partial band bra to a full band bra or vice versa. A pattern alteration is necessary. Does this make sense?
