Either you have a made-to-measure pattern or a purchased one, you might need to apply the shawl collar on your coat or jacket. I will explain here the constructing of the shawl collar when you have a back neck facing.
You should know that the shawl collar is formed of two parts: the undercollar, which is an extension of the front bust pattern, and the upper collar (the visible part), which is actually the front facing.
So if you have followed the pattern instructions, you will have the following pieces: the bust with the undercollar and lapels, the front facing with the upper collar, and the back neck facing.
Here are the steps to apply a shawl collar without tears. Arm yourself with patience and follow the instructions carefully.
1. Apply the interfacing to the wrong side of the garment front. Staystitch the entire neck seamline of the garment. Form the shoulder seams and leave the underarm seams open. (figure 1 )
2. Form the center back seam then press open. Right sides together, match and pin undercollar to garment along neck seamline. Clip garment seam allowance if neccessary for collar to fit smoothly. Garment side up, baste and then stitch undercollar to garment. Remove bastings and press seam flat. (figure 2)
3. Take the two front facing pieces and seam them together in the middle back. Press seam open. Clip into both corners. (figure 3)
4. Match and baste the back neck facing to the front facing, clip back neck facing seam allowance where neccessary and spread front facing at corners. Front facing side up, stitch the seam, reinforcing and pivoting at corners. Press seam open. Notch out both corners of the back neck facing seam allowance, whipstitch these edges together. If necessary, apply a seam finish to the outer, unnotched edge of the entire unit. (figure 4)
5. With right sides together, match and baste the front facing unit built at step 4 to the garment front built at step 1. Stitch from center back down to each half. (figure 5)
6. With under collar and garment side up, understitch outer edge of collar and lapels. With facing side up, understitch each edge of garment opening below the lapels. (figure 6)
7. Roll outer edge of collar toward undercollar. Roll edges of garment opening toward facing. Diagonal-baste along edges. (figure 7)
8. Allow collar and the facing unit to fall smoothly into place. Pin through all layers along the roll line and just above the back neck seamline. Lift up back neck facing and, using a plain-stitch tack, stitch facing and garment neck seamlines together as they fell. Remove pins and tack lower edges of facing to garment.(figure 8)
Here is your pretty collar on your even prettier coat. Did you manage to survive? I think you did of course.