Our corset patterns are made for "average" torso lengths (15.5"-16.5" back neck to waist), which means that you may need to alter the length if you're short or long waisted. If you've made your mockup and determined that you need to adjust the height your corset above the waist, or you regularly need to make length adjustments on commercial patterns, read on.
It may be tempting to just alter the top edge of your corset. That can work sometimes, but it is not ideal. Bust shaping and other important details will not shift and that can result in weird fit issues. The goal here is to add or subtract from the distance between the bust and the hips.
For this tutorial I will cover a short waist adjustment only. The same concepts apply for long waist adjustments, you will just spread your pattern apart on the cut line and tape in extra paper, instead of overlapping your pieces. I am showing an 18th Century pattern since that one is trickiest.
Suggested Tools: pencil, clear plastic gridded ruler, French curve, scotch tape, scrap paper, scissors
Short Waist Adjustment
1. Draw Cut Lines
2. Shorten or Lengthen Pattern
Determine how much you need to adjust your corset. For the purpose of this demo I am shortening these stays 1", so I draw another line 1" above the first.
Cut along the lower lines. Slide the bottom pattern piece up to match the upper line. Be careful to keep your CF, CB, or grain lines even and straight.Tape pieces together.
3. Re-Draw Seams and Boning
Your dashed stitch lines no longer match where you made the adjustment. For straight edges such as the SF seam, you can simply draw a straight line from top corner to bottom corner. This is your new stitch line.
For curved seams, use a French curve to blend the seam line back to original above and below the cut line. Make sure you're following a similar curve to the original pattern.
Tape in extra paper if necessary and re-draw your seam allowance as well.
As you can see, bone placement lines that are not on straight of grain will need to be adjusted as well. Mark a new, straight line from top to bottom corners.
Finally, measure each seam to make sure your pattern pieces still match each other in length. You can true this up at the top edge, blending from one pattern piece to the other (any adjustments will be minor, likely less than 1/4").
That's it! Don't forget to also shorten other pieces like busk pockets, lacing strips, front facings for Victorian corsets. You'll also need to re-work grommet spacing at center back.