Inserting a Trapezoidal Gore
A trapezoidal gore will require at least 1/4″ of un-boned fabric on all sides, plus the width of the top of the gore. For this corset, I have just enough room for a trapezoidal gore with a 3/16″ wide top.
As with the triangular gore, I marked the cut in chalk.
Set your machine to a small stitch, because these stitches need to prevent the layers of the fabric from fraying and pulling free while it is being worked.
Stitch directly down the cut line, across the top the width of the gore top, and back down to the corset edge parallel to the first stitch. These stitches will be cut later, but will serve as a firm guide for all other preparations.
Stitch another line 1/16″ (or a couple millimeters) from the first, and a third line just outside of that one. These stitches will hold the layers of the corset together while inserting the gore.
To draft the trapezoidal gore, draw a rectangle exactly the same size as the part of the corset that will be removed for gore insertion. Leaving the top of the gore the same width as the cut, widen the sides to create the needed extra space. In this case I used a straight-sided trapezoid because the shape of the corset already contains the needed curve. Depending upon your particular fit needs, this gore may have curved sides, or have more bulk to one side or the other.
Be sure to mark the corner points to match when inserting, and add seam allowance. I used a 3/8″ allowance on all sides, including the bottom so I had room to adjust the placement when sewing.
Flatline all layers of the gores so they may be treated as a single unit. These gores are coutil core and silk cover. The flatline stitches are 1/4″ from the gore edges, so there should be 1/8″ overlap of the corset past the stitching.
Cut along the first stitch line to create the insertion for the gore.
Variation: If there is enough room on your panel, you might want to consider a fold-over edge for your gore. However, to do this you will need at least an extra 1/4″ of unboned fabric on all sides, and plan to hand-finish the corners as with the triangular gores. Cut diagonally into the corners back to the fold-over depth so sides and top can all be folded. Don’t forget to include the lost fold-over fabric in your gore when creating the pattern.
I did not have room for a fold-over, so I bound the edges of the insertion area. Stitch the bias tape to the corset 1/4″ from the raw edge.
When you get 1/4″ past the opening, plunge the needle to full depth. Lift the presser foot, turn the corset, and turn the bias tape. Be careful that folds of the bias tape do not pull in front of the needle, or it will create ugly bunching when you go to turn the tape.
Turn again at the other corner.
Stitch all the way down to the edge of the corset.
Fold over the bias tape and top-stitch it in place.
Take care to secure the bias tape all the way around the top edge of the cut.
The underside may be left raw and covered later.
Place the gore under the opening and secure one side. Match the dot so it is just hidden under the body of the corset, and stitch it down.
Secure the top next, and then finish down the other side of the gore.
Once the gore is held in place, stitch at the edge of the binding to further secure it.
Those stitches will hold it while working, but may not be sturdy enough to hold once the corset is being worn. I strongly recommend adding more stitches of some sort to ensure the gore does not pull free. I used a decorative machine stitch, but multiple straight stitches will work just as well. Try to pick something that blends with the overall look of the corset you are modifying.