How to Create a Balanced Dart
A dart that is sewn in heavy or dimensional fabric and pressed to one side can be unattractive and bulky, because you'll have three layers of fabric, one from the garment and two from the dart. These multiple layers may not cause a problem with your new garment, but they will start to shadow through (imprint) on the right side after several washings, dry cleanings, or pressings.
There's no need to cut the dart open to achieve a flat, even effect on both sides of the dart stitching line. Many pattern instructions call for the dart being slit along the length of the fold and pressed open. This involves making a slit in your garment from 10-in. to -12-in. long, which weakens the garment at every double ended dart around the body.
Instead, a balanced dart adds extra fabric to the opposite side of the dart seamline to act as a visual counterbalance. This is also ideal for fabric that ravels easily.
In an unlined garment, the extra fabric to help balance the dart shows and the edges are raw. Cut this extra fabric on the bias, so the edges will not ravel.
|For each dart, cut a bias strip of self-fabric 2-in. wide and 1/2-in. longer than the length of the dart. (I used a contrasting fabric so you can see what is happening easily.)
Fold the garment piece along the center dart in the usual manner.
|Center the length of the fabric strip underneath the garment piece and pin through all thicknesses.
This is the opposite side showing the self-fabric pinned to the dart value.
|Start sewing about 1-in. inside one of the points. Stitch through the point and off onto the bias strip beneath.|
|Stitch the remaining section of the dart, by overlapping your stitching, continue to sew to the remaining point and off onto the fabric beneath.
At the ironing board, fold the fabric in half and press away from the dart.
|Cut away the bulk of the strip up to about 1/8-in. to 1/4-in. away from the fold along the entire length of the fold.|
|From the wrong side, press the dart in one direction and the layers of the trimmed strip on the opposite direction.|
|Press the dart value in one direction and the bias fabric in the dart shape in the opposite direction. This narrow strip is on the bias, and though it is raw edged, it will not ravel. If this narrow strip was serged, the dimension of the serger threads would start to show through to the surface of the garment.|
UPDATE: Threads' senior technical editor Judith Neukam has added additional information to help clarify the process.
|1. The bias strip is a single layer under the dart. Stitch through it when you sew the dart.|
|2. Fold the bias strip along the stitching line away from the garment.|
|3. Open the garment on both sides of the stitching line and press the dart away from the bias strip. You can see that the numbers marking the layers are equal on both sides to balance the dart.|