This has got to be one of my most frequently asked questions: how do you put underwires into a dress? (Especially one like my bombshell dress or other bustier-style design.) Is it possible? To be honest, I really didn't know. So I decided to spend some time exploring the possibility while making B6019, my Butterick Shaheen-style dress pattern. You'll need a pattern with a underbust seam and, ideally, some sort of bra cup seaming.
This pattern is ideal because it has a bodice lining. The underwires will get stitched to the lining only, so that the stitching lines don't show on the outside. If you wanted to put underwires into an unlined bodice, it would need to have actual bra cups (that are the shape of an underwire) or you would have to not care about underwire stitching lines.
Here's how I started. Construct the bodice front lining and add boning channels where desired. Practice positioning the underwires and see if you're happy with how they fit by holding the bodice up to your torso. The underwires should not extend past the top of the neckline. (Tip: you can remove underwires from a worn out bra to avoid having to buy them--plus you'll know they're the right size!)
Place the underwires into channeling. (If you don't have channeling, 1/4" wide bias tape could work in a pinch.)
Mark the underwire placement. It's very important to remember that the underwires will expand when worn. See how I'm stretching them slightly open with my hand in the picture above? This is how you want to mark the placement. Add some chalk lines while stretching the underwire open so you know where to stitch the channeling. The bottom of the underwire should match the underbust seam.
Remove the underwires from the channeling and pin the channeling in place along your marked chalk lines. Stitch along each side of the channeling.
Put the underwire back into the channel and secure the open ends of the channel with stitching. Repeat on the other side of the bust.
Complete the bodice as usual. Here's how the underwired lining looks from the inside.
I ended up adding some thin circular bra pads between the layers for a little extra oomph--the upper cup was collapsing a bit on my smallish bust (sad, I know).
Hope this is helpful! Do you all have any other tips for sewing underwires into a dress?
P.S. This method would work for a swimsuit too!
P.P.S. I'll be back with the sew-along on Monday! I'm going to do a video to show y'all how to make bra straps.