Full Band Vs Partial Band Bras: Part 2
by Maddie Follow

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In part 1 of this series, you learned about the one minor but major difference between the patterns of a full band and a partial band bra, which took  took me about a year to wrap my head around. But how do you put this theory into practice? More specifically, how to do you change a full band bra pattern into a partial band bra pattern? This next part will sound repetitive, I literally copy and pasted it from part 1 of this series, but it’s super important that you understand this concept before you can change a partial band bra pattern to a full band bra pattern or vice versa. For both styles, the wire line or channeling sits in the same spot – at the base of the breast – 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 channeling, which is also almost always ¼”. After the channeling has 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 on 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 wording 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. 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. If you need a visual of this concept, check out part 1 of this series.

So, what is the pattern alteration to change a partial band bra pattern to a full band bra pattern or the other way around? Well, let me show you!

The first step to convert a full band bra pattern into a partial band bra pattern is to add the width of the channeling, which is 1/4″, to the wire line of the upper and the lower cups. Pay extra attention that you don’t add anything at the cross cup seam!

Next, eliminate 1/4″ from the wire line on the band, stopping at approximately at the bottom of the breast (rule of thumb: on a partial band bra, the band should be level with bottom of breast). Next, square down a line equal to the width of the bottom band elastic. Draw a line from this point to CB (center back) and using your eye, create a smooth, curved line that blends to 0″ as shown.

On the bridge, eliminate 1/4″ from both left and right sides of the pattern as well as the top. Just as on the band alteration, stop at a point that is approximately the bottom of the breast. To form the bottom of the bridge, draw a line that connects each bottom point.

Converting a partial band bra pattern to a full band bra pattern is a little more tricky. Because there is no band underneath the cups, we will need to find a way to connect the the band and bridge and more importantly, we will need to find a way to know how far apart to place the two patterns. The solution to this is the underwire.

First, trace the bridge pattern onto a piece of paper with seam allowances included. Next, lay the underwire on the inside edge of the pattern and 1/2″ down from the top edge. After, draw around the inside curve of the wire, extending the point at the underarm 3/4.”

Next, lay the band on the wire so that the top of the pattern reaches the point that was raised 3/4″ past the tip of the underwire. Even if the curve of the band doesn’t match the curve of the underwire, it’s more important that the band touches the +3/4″ point.

Now you can draw a line that connects the band and the bridge. Remember that the minimum amount directly underneath the cup is 3/8″ plus width of the bottom band elastic. Anything less than that and you won’t have room to flip the elastic up when you sew the second pass. Once the bottom of the band is drawn, add 1/4″ seam allowances around the wire line.

Finally, you will need to chose a break point for the band. Because the DOGS (direction of greatest stretch) on the band and the bridge are different (band=horizontal / bridge = vertical), there needs to be a seam so that the fabric’s stretch can be placed accordingly. This can be at either the side seam or underneath the bust point.

The last step is to remove the seam allowance from the upper and lower cup (the opposite of what was done to the cups of the partial band). Again, remember NOT to alter the cross cup seam!

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