Two Ways To Finish Lined Shoulder Seams
When sewing a fully lined garment, the most confusing aspect of sealing the lining layer is handling the shoulder seam area. Depending on the garment's seam location and its design, there are two different techniques you can use to clean finish lining at the shoulder seams:
If the garment has a fully separating center back and center front seam, the shoulder seam on both lining and garment are stitched separately as you would in a conventional manner: fabric face side touching, edges aligning, and seam allowance layers ironed open. The lining and garment layers are then aligned with right sides touching such that the shoulder seams of both garment and lining match up and the armhole and neckline edges align perfectly as shown above. The neckline and armhole edges are then stitched, notched to complete the lined edges.
The lined garment is then pulled through the fully separating seam opening and one of the shoulder areas to flip it completely on its right side. This will naturally enclose all shoulder seam, neckline and armhole raw edges.
Continue understitching the lined edges and iron the finished edges prior to stitching the rets of the seams (with right sids touching) and comeplete the full lining application.
If the garment doe snot have a fully separating seam either on the front or back of the garment, the shoulder seams of both lining and garment layer are left unstitched in the initial lining attachment process. Instead, the side seams of both garment and lining compartments are fully stitched and ironed with the seam allowance layers open. The lining layer is then aligned to the garment layer with fabric right sides touching and all edges of the seam neckline and armhole aligning as shown above. Pins are inserted along along the edges to secure them for machine stitching. The shoulder seams are left unstitched.
When machine stitching the neckline and armhole edges, a 1/2" distance is left unstitched at both ends of the shoulder seam seam edges. This means taht when stitching the armhole and neckline's edges, you should start and end your stitch at about 1/2" form the edge each time.
The lining and garment layers are then flipped on their right sides through the shoulder openings, exposing the clean finished neckline and armhole edges. These edges are then understitched and ironed flat to complete. The shoulder seams are stitched and finished last:
To complete the shoulder seams, align the garment's shoulder seam edges (not lining) with face side stitching as you would with any conventional seam. Insert pins perpendicular to the edge to secure the edges together. Move the lining edges out of the way for now, and repeat the alignment and pinning process on both shoulder seams as shown.
Stitch the garment shoulder seams at the designated seam allowance -1/2" in this case. Be careful not to accidentally catch the lining layers in the process.
Next, fold the lining's shoulder seam edges inwards to enclose all raw edges and pin them in this position to secure. Slipstitch the folded lining edge by hand to either the garment's seam allowance layers underneath or to each other as pictured above.
Once the rest of the garment's seams are complete, the lining should fully encase all fabric raw edges underneath, keeping all seams, especially the shoulder seams, flat, smooth and bulk-free.