Turning a flat piece of fabric into a garment that fits the curves of a human body is the central challenge of tailoring. For the female form, this means creating shape around the bust and waist. The primary tool for this three-dimensional sculpting is the dart.

A standard bodice pattern, or block, typically has darts at the waist and side seam pointing towards the bust apex. This is the starting point. But these darts don't have to stay there. Through a process called dart manipulation, you can move this shaping anywhere on the pattern without changing the overall fit. The most common method is 'pivot and slide'.

While darts are functional, they can interrupt the flow of a garment. A more elegant solution is to convert the darts into shaping seams. This is how you create princess seams, which are curved seams that travel from the shoulder or armhole, over the bust, and down to the waist or hem. A princess seam is essentially a dart that has been extended to become a design feature, creating long, flattering vertical lines.

Creating a princess seam involves splitting the pattern into two or more pieces. You slash the pattern from the shoulder (or armhole) to the bust apex, and from the waist dart up to the bust apex. You then close the original side dart, pivoting its volume into the new slash lines. This separates the pattern into a centre front panel and a side front panel, with the shaping built directly into the seam that joins them.

Commercial patterns are typically drafted for a B-cup size. If the wearer's bust is larger, a Full Bust Adjustment (FBA) is necessary. An FBA adds fabric and shaping to the front of the garment to accommodate the bust, without altering the shoulders, waist, or back. It's a precise alteration that adds volume exactly where it's needed.

This process involves more than just adding width. It also requires adding length to the centre front of the pattern. This is because a larger bust follows a longer path from shoulder to waist. Neglecting to add length will cause the front hem of the jacket to ride up. The goal is to add volume in three dimensions, creating a pocket of space for the bust, ensuring the fabric drapes smoothly without any pulling or gaping.

This kind of careful, anatomical shaping is what separates bespoke tailoring from mass-produced clothing. By manipulating darts and seams, you can create a garment that truly follows the unique contours of the body.