Create the Boning Channels
Your corset is now ready for boning channels. One of the great advantages of dual-core corset construction is the ability to sandwitch boning into the body of the corset without using boning tape, and the ability to place that boning anywhere, regardless of seam locations.
In most cases, it is easiest and most efficient to bone along the seams of a vertical panel corset. If you are not boning along the seams, you will still want to match the seams and pin them together (and possibly baste them as well) before stitching the boning channels This is because you need them lined up to prevent any distortions, bunching, or rippling in the body of the corset. Also, if you choose not to bone along the seams, you will want to make sure of the intended locations of the channels and mark them with chalk before stitching.
This corset is double-boned with 1/4″ spring steel flats at all seams. Double-boning is simply placing two bones side-by-side. I strongly recommend using spiral steel for all your boning except the center front and center back. Spring steel flats only bend in and out, but the spiral steels can twist to smoothly follow all the curves of the body.
To stitch my boning channels, I pinned along the entire length of the Panel5-6 seam, carefully lining up the seams so they fall directly over one another.
Pin baste the body of the corset along the seams. I have bent pins set aside specifically for this purpose. The hooked shape allows them to hold the corset without distorting the fabric (the pins bend around the fabric, rather than the fabric bending around the pins). Another alternative is to buy basting safety pins for quilting.
The first stitch I made was directly along the Panel5-6 seam. I usually begin at the front and work my way towards the back of the corset.
I then moved the pins to the Panel4-5 seams (again, very carefully lining them up), and used the presser foot as my guide to stitch a boning channel on either side of the Panel5-6 seam.
Repeat this procedure for every seam. The image below shows the peg busk half side of the corset, with all seam boning channels sewn.