The most common dart is probably the one often seen at the bustline of women’s blouses. This helps the fabric fit to the woman’s curves, so that the fabric does not look wrinkled or baggy. Princess seaming is also a type of dart, but is much longer and often fits an entire dress bodice lengthwise to the torso. A dart may also be placed in the back of a shirt or blouse to take in fullness through the back or to shape the blouse to the shoulders. This type is usually curved, in order to shape the garment properly.
The bustline dart is generally marked on a sewing pattern as a large “A” shape. The sewer marks the stitching lines on the wrong side of the fabric, usually with a fabric marker or tracing wheel. The dart is made by bringing the lines together, which creates a triangular fold on the wrong side of the fabric. The fold can then be pinned into place, and the sewer stitches the fabric together, beginning at the widest part of the dart and going to the point. Care should be taken not to let the stitches or thread pucker, so the dart will be smooth on the outside.
A dart may either be pressed down and to one side, or the fold can be centered over the seam and the excess material flattened out and pressed, making two folds. How the dart is pressed will depend on the garment, fabric and fit. For a shoulder or back dart, the sewer will usually mark curved, rather than straight, lines, and will follow the same construction and sewing directions, always being careful to keep the seam straight and smooth. A sewer should never hurry while making a dart, since these details often mean the difference between a well or poorly fitting garment.
Most sewers learn to make darts in a beginning sewing class. Instructions with pictures are also available online, but the best way to make a first one is usually to do it under the watchful eye of an experienced sewer.