Chapter 13

The bra

A bra is the most precise garment there is. A few millimetres change how it fits, so every step is measured, and a test bra comes before the real one.

The cup is a dome over the base of the breast, split into a lower and an upper cup. Its size comes from the difference between the bust and the underbust. The frame holds the wire, which lies flat on the ribcage round the whole breast. The band carries most of the support, around four fifths of it; the straps only a small part.

What you need

Drafting, step by step

Each picture shows everything drawn so far; the new line of the step is in colour. The formulas show the names of the measurements first, then the numbers for size 38.

1. Cup

   Step 1

   Cup projection

   (Bust − Underbust) × 0.45 + cup depth adjust

   = (88.0 − 75.0) × 0.45 + 0.0 = 5.9 cm

   The difference between the bust and the underbust is the cup size. It sets how far the cup stands out from the ribcage. Each 2 to 2.5 cm of difference is one cup size.

2. Step 2

   Breast root width

   Underbust × 0.13 + (Bust − Underbust) × 0.2 + wire width adjust

   = 75.0 × 0.13 + (88.0 − 75.0) × 0.2 + 0.0 = 12.4 cm

   The wire sits round the root of the breast. Check it on the body: lay a wire under the breast and see that it neither sits on the breast tissue nor stands away from it at the side.

3. Step 3

   Cup radius over the surface

   apex to the wire, measured over the breast: 9.4 cm

   The cup is a dome over the root. Its height and width give the distance from the apex down to the wire, measured over the surface.

4. Step 4

   Cross-cup seam

   each ring keeps its length on the body: 20.5 cm

   Round the apex the flat paper is too long for the dome. Each ring is shortened to its length on the body, so the seam curves; sewn to the upper cup it shapes the dome.

5. Step 5

   Wire line

   half the root circle: 19.4 cm

   The lower edge sits on the wire. It has the same length as the wire line on the frame.

6. Step 6

   Outline of the lower cup

   The lower cup: wire line below, cross-cup seam above, the apex notched.

7. Upper cup

   Step 6

   Strap point and neckline

   upper cup coverage = 0.8

   The upper cup is the same dome turned up. The neckline is cut lower for a balconette, higher for a full cup; the strap sits towards the side so it runs over the shoulder.

8. Step 8

   Outline of the upper cup

   The upper cup. Sew it to the lower cup along the cross-cup seam, matching the apex notches.

9. Front frame

   Step 7

   Centre gore

   centre gore width = 1.8

   The gore is the bridge between the cups. It should lie flat on the breastbone; if it stands away, the wire is too narrow or the cup too small.

10. Step 8

    Wire opening

    a U the width of the breast root: 19.4 cm

    The cup is sewn into this opening. Its length matches the wire line of the lower cup, so the two go together without easing.

11. Step 9

    Side frame

    side frame width = 3.0

    The side frame holds the wire against the ribcage under the arm. It is cut from a firm fabric that does not stretch.

12. Step 12

    Outline of the front frame

    The front frame, cut on the fold at the centre front and lined with a firm, non-stretch fabric.

13. Back band

    Step 10

    Band length

    (Underbust + band stretch taken off) ÷ 2 − front frame

    = (75.0 + -8.0) ÷ 2 − 16.3 = 17.3 cm

    The band carries most of the support. It is made smaller than the underbust and cut in power mesh, so it stretches round the ribcage and holds the frame flat against the body.

14. Step 14

    Outline of the back band

    The back band in power mesh, the greatest stretch running along the band.

The finished pieces

Sewing it

1. Cut and mark. Cut every piece with the grain arrow parallel to the selvedge. Transfer the notches and the marks with tailor's chalk or a short snip into the seam allowance.
2. Materials. Cups: a firm, non-stretch fabric or cut-and-sew foam, lined. Frame: firm fabric lined with stabilised tricot. Back band: power mesh with the stretch along the band. You also need underwires, channeling, plush underband elastic, narrow top elastic, strap elastic with rings and sliders, and hook and eye tape.
3. Cups. Sew the upper cup to the lower cup along the cross-cup seam, matching the apex notches. Press the seam allowances apart and topstitch them down on both sides. Do the same with the lining and place it inside, wrong sides together.
4. Neckline edge. Finish the neckline edge of the upper cup with narrow elastic or a fold-over binding, without stretching it.
5. Frame. Baste the frame to its lining. Sew the back bands to the frame at the side seams.
6. Cups into the frame. Sew each cup into the wire opening, cup on top, matching the centre front, the bottom notch and the side. Clip the frame allowance so it turns smoothly.
7. Channeling. Stitch the channeling over the seam allowance of the wire line from the centre gore round to the side. Leave the top ends open.
8. Underband elastic. Zigzag the plush elastic to the right side of the band edge, the plush facing up. Turn it to the inside and topstitch with a three-step zigzag, stretching it slightly along the back bands.
9. Top edge. Finish the top edge of the back bands and the side frame with narrow elastic in the same way.
10. Wires. Slide the wires into the channeling. Close each end with a bar tack across the channel just above the wire tip.
11. Straps. Sew a ring to each strap point on the upper cup. Thread the strap elastic through the slider and the ring and stitch it to the back band at the strap mark.
12. Hooks. Sandwich the ends of the back bands in the hook and eye tape and stitch them in.