Balanced dart is another couture technique I used in my Gucci-inspired dress. It is not difficult and results in a perfectly flat seam with the bulk distributed equally on both sides of it.
This technique is required only when you work with fabrics that create noticeable bulk in darts. It was described in a few sources, such as Threads magazine, Claire Schaeffer’s books, as well as in a few vintage sewing books. I think, however, that the best method for a balanced dart is demonstrated in Thomas von Nordheim’s Vintage Couture Tailoring.
To do a balanced dart you will need only a bias strip of self-fabric, long enough to extend beyond dart tips by approximately 2.5 cm (1").
Why bias? A strip cut on bias is more (a) flexible and (b) doesn’t ravel as easily
Now, before I demonstrate a step-by-step technique, let’s talk how the dart should be prepared for a flawless result. You can mark the dart using tailor tacks or basting stitch (called tacking in tailoring). I thread-traced the dart because it stabilizes both layers: fashion fabric and underlining.You should also mark both dart ends by thread tracing. This is called balance mark.
BASTE THE DART
Baste the dart using preferably different color basting thread and using shorter stitches. At this point you can remove thread tracing (it will be easier if it was done in a contrasting color), but leave balance marks.
Place a bias strip of self-fabric under the dart fold, with the dart width points aligned with the strip center.
Machine stitch the dart through the strip, starting on the strip, and, then, hitting the dart at the balance mark and following the basting dart. Finish the stitching the same way, stitching through the dart point and finishing on the strip of self-fabric. This method will not only allow you to avoid backstitching, but also makes it easier to get accurate dart points.
From the wrong side, softly press the fullness of the dart to one side, and the two layers of the self-fabric strip to the other. Now, the dart bulk is distributed equally and there is no bulge on either side of the seam. Don’t press from the right side yet, because the dart needs to be finished
At each dart end, clip into one layer of the bias strip, creating a half-arrow shape ending at the dart end. Fold over the clipped portion over the dart. Trim excess fabric, so the widths of the dart and the strip approximately match, grading the seam allowance of the bias strip, so the width difference of the two edges is about 3mm.
Give the dart final press from both sides of the fabric. On the right side, press through a self-fabric press cloth to avoid marks.